Tokyo Prefecture reaches far beyond the skyscrapers of the 23 wards, stretching some 600 kilometers south into the Pacific as a chain of volcanic islands. On Oshima, Niijima, Shikinejima, Kozushima, Miyakejima, and Hachijojima, sodium chloride and simple thermal springs rise straight from volcanic bedrock, and at least one spring is reachable only by chartered fishing boat when the tide and weather happen to align. Back on the mainland, a very different onsen tradition survives in the low-rise neighborhoods of Ota and Shinagawa wards, where century-old sento draw dark, mineral-rich "black water" (kuroyu) from strata laid down over a million years ago. Few prefectures anywhere in Japan pair untouched island wilderness with urban bathing culture inside a single administrative boundary. Below are 10 of Tokyo's most distinctive hot springs, spanning remote islands, a mountain lakeside inn, and neighborhood bathhouses.
1. Oshima Onsen Hotel (大島温泉ホテル, Mihara-yama Onsen) — Oshima, Izu Islands
Mount Mihara, the active volcano at the heart of Izu Oshima Island, rises from the sea as a symbol of the island's fiery origins. Perched on its outer rim at an elevation of roughly 500 meters stands Oshima Onsen Hotel, the only lodging on the island built directly within the embrace of the volcano. Open since April 1959, the hotel is one of the longest-standing hot spring establishments in the Izu Islands. To draw hot water from deep within the volcanic bedrock, the property sank a borehole some 300 meters underground, delivering the mountain's own volcanic blessing straight into its baths.
The water rises from the source at a scorching 84.2 degrees Celsius with a neutral pH of 6.6, classified as a simple thermal spring (a hypotonic, neutral, high-temperature spring). Because the water is already far hotter than needed, it requires no artificial heating and is simply left to cool before flowing into the tubs. Served free-flowing, without dilution or recirculation, the clear, colorless water carries a texture visitors often describe as strangely nostalgic. It is said to ease neuralgia, muscle and joint pain, frozen shoulder, bruises, and sprains.
The bathing facilities include a panoramic indoor bath and an elegant open-air bath, both separated by gender. The outdoor bath in particular offers a sweeping view of Mount Mihara's caldera through the surrounding virgin forest, letting bathers soak while facing the volcano itself in dramatic isolation. All 22 guest rooms are Japanese-style with private bath and toilet. Dinner features the hotel's signature camellia fondue alongside other island specialties, and the breakfast buffet is a particular favorite among guests.
Day-trip bathing is available year-round for 800 yen per adult and 400 yen per child, in two sessions -- 6:00 to 9:00 in the morning and 13:00 to 21:00 in the afternoon and evening. The hotel offers free parking for 50 cars, and its accessibility is a real draw: about 1 hour 45 minutes by Tokai Kisen jet boat from Takeshiba Pier in Tokyo, or about 15 minutes by shuttle bus from Oshima Airport. Serving as an ideal base for trekking Mount Mihara or exploring the island's black-sand Ura-Sabaku desert, it is a hotel where bathing becomes inseparable from the raw, volcanic grandeur of the island itself.
Quality
Simple Hot Spring
Temp
40℃ to 44℃
Emerge
Pumped
Supply
Natural Source Flow
Heat
Not Heated
pH
pH 6.6
0714
AcidicNeutralAlkaline
Use
Stay OK/Day Trip OK
Fee
Adult 800JPY/Child 400JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 13:00 - 21:00 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
2. Tsurunoyu Onsen (鶴の湯温泉, Ogouchiso) — Okutama, Nishitama District
On the quiet shore of Lake Okutama stands a small inn called Ogouchiso, where guests can soak in Tsurunoyu Onsen, a hot spring said to date back to the Enbun era of the Nanboku-cho period (1356-1361). Legend has it that an injured crane once healed its wounds in these waters, giving the spring its name, and it has long been cherished by the local community. Three separate sources once fed a small hot spring village here, but the entire settlement was submerged when the Ogouchi Dam was built to create Lake Okutama, and the spring became known for years as a 'phantom hot spring.' Remarkably, in 1991 the submerged pumps were repaired, and the three sources were combined and drawn up together, bringing the spring back to life.
The water is classified as an alkaline simple sulfur spring, with a strikingly high measured pH of 9.68 that leaves the skin feeling wonderfully smooth. The source emerges at a modest 30.2 degrees Celsius, technically a low-temperature spring, and carries a faint sulfurous, egg-like aroma. Though perfectly clear and colorless, its gentle effect on the skin is easy to notice after bathing. Since the source is too cool for direct use, the water is warmed before reaching the tubs, allowing visitors to savor this once-vanished spring in comfort.
Built entirely of cypress, the two-story Ogouchiso houses two distinctively different baths: a fragrant cypress-wood bath on the second floor and a bath featuring rare chrysanthemum stone on the first. The two baths alternate between men and women each morning and evening, meaning guests staying overnight can enjoy both during their visit. All guest rooms are traditional tatami rooms equipped with air conditioning, a refrigerator, and a safe. Dinner and breakfast are served in private dining rooms, offering a relaxed stay wrapped in mountain quiet.
As a small inn operating strictly by reservation with room for only eight guests at a time, booking ahead by phone is essential. A one-night stay with two meals costs 12,250 yen per adult (bathing tax included), payable in cash only. The inn closes every year from December 20 through the end of February, so it is worth confirming the operating season before planning a visit. With its tranquil setting overlooking Lake Okutama and its rare sulfur spring revived from the depths, Ogouchiso is a hidden gem for travelers seeking a genuine, unhurried hot spring retreat away from the crowds.
Quality
Simple Sulfur Spring
Emerge
Pumped
Heat
Heated
pH
pH 9.7
0714
AcidicNeutralAlkaline
Use
Stay OK/Day Trip N/A
Book your stay
3. Mamashita Onsen (まました温泉) — Niijima, Izu Islands
Just a ten-minute walk from Niijima Port, in the Setoyama district near the gateway to this Izu Islands outpost south of Tokyo, sits Mamashita Onsen, a day-use bathhouse long cherished by locals. It was opened by the village in 1983 as a place for residents' training, rest, and health promotion, and in fiscal 2002 the facility added its now-signature sand bath. Parts of the building incorporate kokaseki, a volcanic stone unique to Niijima, giving the structure a distinct sense of the island's geology.
The spring's defining trait is its source temperature of 79.8°C, a sodium chloride spring with an almost neutral pH of 6.86. Like seawater, the water carries a pronounced salty taste, and it is rich in metasilicic acid, prized for its skin-softening effect. The high mineral concentration warms bathers to the core, and the lingering flush after leaving the tub means the bath rarely leaves you feeling chilled afterward — a trait that keeps repeat visitors coming back.
The bathhouse offers an indoor bath, an open-air bath, and a free sauna, with the open-air bath's view considered among the finest on Niijima. Mamashita Beach stretches out below, with Shikinejima and even Kozushima visible in the distance, and at dusk the Pacific sunset turns the water a deep amber. Next door, a sand bath uses white sand carried from Hafuura Beach and warmed by the hot spring water, with the sand itself replaced twice a year for cleanliness.
The facility is open from 13:00 to 21:00 (last entry 20:30) and closed every Wednesday. Admission is an affordable 300 yen for adults, 150 yen for elementary school children, and 200 yen for those 70 and older, reflecting its role as a community bathhouse; the sand bath costs an additional 700 yen for adults and 400 yen for children. Only cash is accepted, so bring exact change. Niijima can be reached by Tokai Kisen ferry from Takeshiba Pier in Tokyo or by a short flight from Chofu Airport, making the onsen a pleasant stop alongside sightseeing or beach time at nearby Hafuura Beach.
Quality
Sodium - Chloride Strong Salt Spring
Temp
42℃ to 46℃
Supply
Natural Source Flow
Heat
Not Heated
pH
pH 6.9
0714
AcidicNeutralAlkaline
Use
Stay N/A/Day Trip OK
Fee
Adult 300JPY/Child 150JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 13:00 - 21:00 | ◯ | ◯ | × | ◯ | ◯ | ◯ | ◯ | ◯ |
4. Shikinejima Mikawawan Kaichu Onsen (式根島 御釜湾海中温泉) — Shikinejima, Izu Islands
Shikinejima, one of the Izu Islands, is sometimes called 'the island of hot springs' for its abundance of wild, rustic bathing spots, including well-known coastal onsens like Jinata and Ashitsuki. Standing apart from all of them is the Mikawawan Kaichu Onsen, quietly bubbling up offshore in Mikawa Bay. Local fishermen are said to have long noticed steam rising from a crack in the cliffside rocks just above the waterline, though no reliable record states who first discovered it or when. It shot to national fame after being featured on the television program 'Tokoro JAPAN,' and has since become a bucket-list destination for onsen enthusiasts and divers across Japan who know it as a 'phantom hot spring.'
The main reason this spring earns its 'phantom' reputation has less to do with its water quality than with the sheer difficulty of reaching it. It is said to be a sodium chloride brine spring, colorless and transparent, carrying a faint whiff of hydrogen sulfide along with the salty tang of the sea. The source bubbles up from sandy patches on the seafloor and cracks in the cliff rock at a reported 75 to 90 degrees Celsius, hot enough to burn bare skin on contact and far too hot to bathe in directly. Only in the brief moment when the incoming tide mixes seawater with the spring does a small, comfortably warm pool form. Hunting for that perfect pocket of warmth is both the spring's greatest thrill and its greatest challenge.
There is nothing resembling a conventional bathhouse here, no changing rooms, no fences, no signage, only the open ocean, a sheer cliff face, and white sea spray. Visitors charter a fishing boat from Shikinejima Port out to the waters off Mikawa Bay, then leave the boat behind and swim the rest of the way themselves. Among scuba divers, the site is known as one of Japan's rare 'hot spring dive spots,' where bubbles of geothermally heated water can be watched rising from a white sandy seabed at depths of roughly 12 to 23 meters, and lucky divers sometimes spot sea turtles gathering to bask in the warmth. There are no facilities whatsoever, but that absence is precisely what makes the encounter with raw nature so intense.
Anyone planning a visit needs to fix their sights on a day when four conditions align at once: a spring tide, low tide, dead-calm seas, and clear weather. Such days come only a handful of times a year, and even the island's own fishermen are cautious about declaring 'today is the day.' The safe window for bathing is confined to the short span around low tide; once the tide turns, waves push in and the danger rises sharply, so lingering is strongly discouraged. Anyone unsure of their swimming ability or physical fitness should not push their luck, and should instead consider other wild onsens reachable on foot, such as Jinata or Ashitsuki. Whoever does attempt the visit should check current sea conditions with local fishermen or the tourism association beforehand, avoid going alone, and take full safety precautions such as wearing a life jacket.
Quality
Sodium - Chloride Strong Salt Spring
Temp
35℃ to 90℃
Emerge
Natural Emergence
Supply
Natural Source Flow
Heat
Not Heated
Use
Stay N/A/Day Trip OK
Fee
Adult ---JPY/Child ---JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 00:00 - 23:59 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
5. Nakanogo Onsen Yasuragi no Yu (中之郷温泉 やすらぎの湯) — Hachijojima, Izu Islands
Hachijojima, one of the southernmost of the Izu Islands, has long been known as a hidden gem far south of Tokyo, dotted with a handful of hot springs across its volcanic landscape. Nakanogo Onsen Yasuragi no Yu is a public bathhouse run by the town of Hachijo in the Nakanogo district on the island's eastern side, affectionately known to locals simply as Yasuragi. Its water comes from a drilled source called the Nakanogo Onsen No. 2 Well, carrying on the island's tradition of salty, sea-adjacent hot springs.
The bath is filled with a clear sodium chloride spring water, drawn at a source temperature of 45.7°C with a pH of 6.0. Rich in seawater-like minerals, the water is slightly diluted to reach a comfortable bathing temperature before flowing continuously into the tub, giving bathers a silky, warming soak typical of the island's springs. Like most of Hachijojima's hot springs, Yasuragi no Yu belongs to the chloride-spring family prized for keeping the body warm long after leaving the bath.
The bathhouse itself is modest in size, but its separate men's and women's indoor baths, each fitted with a cypress-wood tub, open onto large windows facing the Kuroshio Current. On clear days, bathers can spot the silhouette of Aogashima Island roughly 67 kilometers to the south while soaking in an uninterrupted view of the open Pacific. A free massage chair awaits in the rest area, and shampoo, body soap, and hair dryers are all provided, making it an easy, no-fuss stop for travelers without their own toiletries.
The bath is open from 10:00 to 21:00 (last entry 20:30) and closed on Thursdays, except during public holidays, the summer season, and the New Year period. Admission is a remarkably affordable 300 yen for adults and 100 yen for elementary school children and town residents aged 70 and over. It sits about 18 minutes by car from Hachijojima Airport and 21 minutes from Sokodo Port, making it a convenient stop between sightseeing or hikes up Mt. Hachijo-Fuji and Mt. Mihara. Thanks to the Kuroshio Current's moderating effect, Hachijojima stays relatively mild even in winter, so the ocean view from the bath is worth enjoying in any season.
Quality
Sodium - Chloride Spring
Temp
42℃ to 46℃
Supply
Natural Source Flow
Heat
Not Heated
pH
pH 6
0714
AcidicNeutralAlkaline
Use
Stay N/A/Day Trip OK
Fee
Adult 300JPY/Child 100JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 10:00 - 21:00 | ◯ | ◯ | ◯ | × | ◯ | ◯ | ◯ | ◯ |
6. Kozushima Onsen Hoyo Center (神津島温泉保養センター) — Kozushima, Izu Islands
Kozushima Onsen Hoyo Center sits on the rocky southwestern coast of Sabisaki, on Kozushima Island -- a small volcanic island roughly 180 kilometers south of central Tokyo near the middle of the Izu archipelago. The site's first bath, the open-air Sabisaki Onsen, opened in 1988, and the facility was rebuilt and reopened as the current Kozushima Onsen Hoyo Center in 1994. Like the rest of the Izu Islands, Kozushima was shaped by volcanic activity, and the concentrated chloride spring bubbling up from its shoreline is a direct reminder of that fiery origin.
The spring is classified as a sodium chloride strong salt spring, drawn from a source measuring 56.5°C with a neutral pH of 7.37. The spring yields an abundant 420 liters per minute, and its total mineral content reaches 34.76 grams per kilogram -- a concentration nearly matching seawater, salty enough to taste on the lips. The water is supplied on a source-fed, non-recirculated basis (kake-nagashi) to both the indoor and outdoor baths, diluted slightly with fresh water to bring the temperature down to a comfortable soak. Thanks to its high salt content, the water has a strong warming effect that lingers long after leaving the bath.
The highlight is a spectacular 275-square-meter open-air bath carved into the natural rock, one of the largest in the Izu Islands and spacious enough for over a hundred bathers at once. Two more outdoor baths round out the collection -- one overlooking Sawajiri Bay, and a roofed observation bath -- for three distinctive open-air pools in total. Because all of the outdoor baths are mixed-gender, swimsuits are required (rentals are available for 500 yen). Indoors, gender-separated baths offer bubble baths, jet showers, and pressure-jet tubs, all likewise fed directly from the source. A sauna, a foot bath, and an on-site restaurant round out a facility built for a leisurely full day of soaking.
The center is open from 11:00 to 20:00 (last admission 19:00) and closes on Wednesdays -- except during the July-September summer season, Golden Week, and the New Year holidays, when it operates daily. Admission is an affordable 800 yen for adults and 400 yen for children. From Kozushima Port, the village's West Coast bus route takes about 10 minutes to the 'Onsen Hoyo Center-mae' stop, or it's a roughly 40-minute walk. Evening visits are especially rewarding, since the outdoor baths offer clear views of a star-filled sky after dark. Getting to Kozushima takes some effort -- about four hours by jet boat from Takeshiba Pier in Tokyo, or 45 minutes by small propeller plane from Chofu Airport -- but the reward is a genuinely remote hot spring well worth the journey.
Quality
Sodium - Chloride Strong Salt Spring
Temp
42℃ to 57℃
Supply
Natural Source Flow
Heat
Not Heated
pH
pH 7.4
0714
AcidicNeutralAlkaline
Use
Stay N/A/Day Trip OK
Fee
Adult 800JPY/Child 400JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 11:00 - 20:00 | ◯ | ◯ | × | ◯ | ◯ | ◯ | ◯ | ◯ |
7. Furusato no Yu (三宅島 ふるさとの湯) — Miyakejima, Izu Islands
Miyakejima is a volcanic island roughly 180 kilometers south of central Tokyo, sitting near the middle of the Izu archipelago. On its western shore, on a bluff in the Ako district, lies Furusato no Yu, the island's only hot spring. Built in 1995 by Miyake Village as the centerpiece of the 'Furusato Experience Village' complex, the bathhouse was forced to close when the 2000 eruption of Mount Oyama triggered an island-wide evacuation that kept residents away from their homes for nearly five years. After the evacuation order was finally lifted in 2005, the facility reopened in June 2007, and today it serves as both a cherished gathering place for islanders and an essential stop for visitors passing through.
What sets this spring apart is its color. Classified as a sodium chloride strong salt spring, the water emerges from its source at 43.5°C with a neutral pH of 6.5. A trace of dissolved iron oxidizes on contact with air, tinting the entire bath a warm, tea-like brown -- a striking contrast to the clear chloride springs found elsewhere in Japan, and a direct expression of the volcanic soil that shaped this island. The water is salty enough to taste distinctly on the lips, and its mineral concentration gives it a powerful warming effect that lingers well after bathers step out of the tub.
The facility offers one outdoor bath and two gender-separated indoor baths. The indoor baths are fitted with large glass windows that frame an open view of the Pacific horizon while soaking. But the real highlight is the sunset visible from the outdoor bath: thanks to the island's western-facing position, the setting sun sinks directly into the ocean horizon each evening, painting both sky and sea in deep shades of amber and red -- a view best enjoyed while submerged in the warm, brown-tinted water.
Hours run 11:00-21:00 from April through September and 11:00-20:00 from October through March, with the facility closed on Wednesdays (open daily in August). Admission is an affordable 500 yen for adults and 250 yen for children (ages 6-11), discounted further to 150 yen on the 26th of every month. Reaching Miyakejima takes about 50 minutes by small aircraft from Chofu Airport, or roughly six and a half hours by overnight ferry from Takeshiba Pier, so most visits involve an overnight stay rather than a simple day trip. All the more reason to make time on the island for a quiet soak in this iron-tinted water at dusk, watching the sun disappear into the Pacific. The facility is also barrier-free, making it an accessible retreat for visitors of all ages.
Quality
Sodium - Chloride Strong Salt Spring
Temp
40℃ to 44℃
pH
pH 6.5
0714
AcidicNeutralAlkaline
Use
Stay N/A/Day Trip OK
Fee
Adult 500JPY/Child 250JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 11:00 - 21:00 | ◯ | ◯ | × | ◯ | ◯ | ◯ | ◯ | ◯ |
8. Musashi-Koyama Onsen Shimizu-yu (武蔵小山温泉 清水湯) — Shinagawa Ward
Tucked just off the lively Musashi-Koyama shopping street in Shinagawa Ward, Tokyo, Musashi-Koyama Onsen Shimizu-yu is a neighborhood sento that has been run by the same family for three generations since its founding in 1924. Back when conventional wisdom held that no hot springs exist in Shinagawa, the second-generation owner, facing a struggling business, took a bold gamble and drilled for a spring anyway. In 1994, the effort paid off with a black-water spring struck at a depth of 200 meters, and customer numbers reportedly tripled overnight. His successor, third-generation owner Taro, later reasoned that a bathhouse might as well have a second hot spring, and in 2007 drilled an even deeper 1,500-meter well, striking one of Tokyo's most concentrated therapeutic springs, Ogon-no-Yu, the Golden Spring. Having two chemically distinct sources beneath a single sento is rare nationwide, and the bathhouse is recognized as the first in Japan to be certified as both a deep-source hot spring and a therapeutic spring, drawing onsen enthusiasts and certified onsen meisters from across the city.
The defining feature of Shimizu-yu is the chance to soak in two utterly different natural hot springs under one roof. Kuro-yu (Black Spring) is a metasilicic-acid-rich sodium bicarbonate mohru spring drawn from strata over a million years old, with a source temperature of 18.6 degrees Celsius and a pH of 8.3. Loaded with humic acid and minerals, it emerges a deep amber-brown with the distinctive toasty scent of mohru water; because the source runs cool, it is heated, circulated, and chlorine-treated, with high-concentration nanobubbles infused to soften the water against the skin. Ogon-no-Yu (Golden Spring), by contrast, rises from 1,500 meters below ground as an ancient-seawater-derived, hypertonic sodium chloride spring, with a source temperature of 38.0 degrees Celsius, a pH of 7.8, and an intensely concentrated 18.66 grams of dissolved minerals per kilogram, including abundant iodine. Its deep milk-tea color carries a faint petroleum-like scent, and it is delivered straight from the source with no dilution or added heat. Few places anywhere let bathers compare two genuinely different hot springs, in mineral makeup, color, and aroma, side by side in a single visit.
The bathing area is modest in size but cleverly laid out. The open-air bath is arranged on two levels, with Ogon-no-Yu on the upper tier and Kuro-yu on the lower, letting bathers move between the two and feel the contrast directly; six deck chairs invite lingering in the evening breeze afterward. The indoor bath features a hyper jet bath, an electric bath, and a jacuzzi, while a roughly 90 degree Celsius dry sauna paired with a cold plunge pool draws its own loyal following. Upstairs, a women-only ganban-yoku rock-bed sauna (1,500 yen for 45 minutes) and a free rest area are available, and the front desk sells the bathhouse's signature hot-spring eggs, drinks, and snacks. Despite sitting in a corner of the down-to-earth Musashi-Koyama shopping street, the facility delivers the satisfaction of a full-fledged onsen destination, which is precisely why it draws both loyal locals and hot-spring enthusiasts from far afield.
The bathhouse is open 12:00-24:00 on weekdays, Saturdays, and public holidays, and from as early as 8:00-24:00 on Sundays, with Mondays as the regular closing day (open instead if Monday is a public holiday). At sento-level prices, 550 yen for adults, 500 yen for junior high schoolers, 200 yen for elementary schoolers, and free for infants, the chance to enjoy two genuine natural hot springs is remarkable value. It's a five-minute walk from Musashi-Koyama Station on the Tokyu Meguro Line and about five minutes by car from the Ebara-machi exit of the Shuto Expressway Route 2, with on-site parking for 10 cars (free for the first two hours), making it an easy stop after work or while shopping in the arcade. Since it stays open late into the night, visitors hoping to avoid weekend crowds might do best to arrive right at opening on a weekday or late at night. Anyone visiting Musashi-Koyama should make a point of comparing the two springs firsthand, Kuro-yu and Ogon-no-Yu, rather than settling for just one.
Quality
Sodium - Bicarbonate Spring
Sodium - Chloride Strong Salt Spring
Temp
40℃ to 42℃
Emerge
Pumped
Supply
Partial Natural Flow
Heat
Heated
pH
pH 8.3
0714
AcidicNeutralAlkaline
Use
Stay N/A/Day Trip OK
Fee
Adult 550JPY/Child 200JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 12:00 - 24:00 | × | ◯ | ◯ | ◯ | ◯ | ◯ | 08:00-24:00 | ◯ |
9. Kamata Onsen (蒲田温泉) — Ota Ward
Kamata Onsen is a long-established neighborhood bathhouse (sento) that opened in 1937 in the Kamata-Honcho district of Ota Ward, Tokyo. In the postwar years, patients from a nearby hospital reportedly visited for therapeutic bathing, and the bathhouse has long served as a community hot-spring retreat. The current building dates from 1986, and while the interior retains a nostalgic, retro atmosphere, it is kept impeccably clean despite the facility's nearly nine decades of history. Tucked into a residential block a short walk from both Keikyu-Kamata and JR Kamata stations, it draws not only local regulars but also onsen enthusiasts who travel from afar specifically for its famous black water.
The spring is classified as a sodium bicarbonate-chloride spring. Pumped up from deep underground, the black water (kuroyu) is rich in humic acid and other organic matter deposited in ancient sediment layers, giving the bath an inky, coffee-like darkness. Among the many black-water onsens scattered across Ota Ward, Kamata Onsen's water is often cited as among the darkest and most concentrated in all of Tokyo — dip a hand in and your fingertips disappear just centimeters below the surface. Because the source itself is a cool mineral spring at around 18°C, the water is heated before use and, for hygiene, is also filtered through a circulation system and chlorinated. Bathers describe a silky texture and a faint mineral scent, with skin left noticeably smooth afterward.
The bathing area features both hot and cool pools of black water, an electric bath, a jet bath, a cold plunge, and separate saunas for men and women — a well-rounded lineup for a day-trip bathing facility. The second floor houses the Kamata Onsen cafeteria and a banquet hall complete with a stage, preserving the old-fashioned sento culture of relaxing with a drink after a soak. A hand-free visitor set (800 yen, including admission, a towel, and loungewear) means guests can drop in on a whim without bringing a change of clothes.
The bathhouse is open year-round from 10:00 a.m. to midnight, with adult admission a reasonable 550 yen. It's accessible on foot or by bus from both JR Kamata and Keikyu-Kamata stations; free parking is limited to just two spaces, so public transport is recommended. The crowd shifts through the day — weeknight visitors stopping for a soak and a drink after work, weekend afternoons drawing families and neighbors. Being close to Haneda Airport, it's also a popular stop for travelers looking to unwind in the black water before or after a flight.
Quality
Sodium - Bicarbonate - Chloride Spring
Emerge
Pumped
Supply
Circulation System
Heat
Heated
Use
Stay N/A/Day Trip OK
Fee
Adult 550JPY/Child 200JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 10:00 - 24:00 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
10. Keio Takaosan Onsen Gokurakuyu (京王高尾山温泉 極楽湯) — Hachioji
Mount Takao is often called Edo's back parlor for its closeness to the city, but at its core it is a mountain of faith with more than 1,300 years of history. Yakuoin Temple, said to have been founded in 744 under an imperial decree from Emperor Shomu and built by the priest Gyoki as a temple for the protection of eastern Japan, sits at its heart. In the Eiwa era (1375-1379), the ascetic Shungen arrived from Daigoji Temple in Kyoto and enshrined Izuna Gongen as the mountain's guardian deity, and from then on Mount Takao flourished as a center of Izuna worship and Shugendo mountain asceticism. Because tengu are considered attendants of Izuna Gongen, the mountain is also known as a home of tengu, and its two waterfalls, Biwa Falls and Jaryu Falls, still welcome ordinary practitioners for ritual purification under falling water today. Keio Takaosan Onsen Gokurakuyu, opened in 2015, is a comparatively young facility, but sitting immediately outside the ticket gates of Takaosanguchi Station, the gateway to this sacred mountain, it links the experience of pilgrimage and hot spring bathing into one seamless visit.
The water here is an alkaline simple hot spring with a striking pH of 9.9. The source temperature is a relatively cool 26.2 degrees Celsius, but the flow rate is a generous 300 liters per minute, drawn from the operator's own well struck at a depth of roughly 1,000 meters after drilling that began in October 2012. The open-air rock bath that uses the genuine spring water is only heated, never diluted or circulated, preserving the source water in its natural state, and its silky, smooth texture has earned the bath a reputation as a spring for beautiful skin. The water is faintly white and clear, with a subtle sulfurous scent that evokes the atmosphere of a true mountain hot spring.
The bathing facilities are varied. Outdoors, bathers can choose between lukewarm and hot versions of the natural hot spring rock bath, alongside a rare artificial carbonated stone bath rarely found in Japan. Indoors, a microbubble silk bath, a seasonally rotating bath, a far-infrared sauna, a sitting bath, and a cold plunge bath round out the offering, giving hikers a thorough way to soothe legs tired from the climb. After bathing, visitors can enjoy a light meal such as grated yam soba at the on-site restaurant, or relax in the nap lounge or a paid private tatami room.
The facility's greatest appeal is its unbeatable access, sitting immediately next to the ticket gates of Takaosanguchi Station on the Keio Takao Line. Visitors can walk in wearing their hiking boots just steps from the platform, with no need to travel anywhere after working up a sweat on the mountain. It is open from 8:00 to 22:30 (last entry 21:45) year-round, with admission of 1,100 yen for adults on weekdays and 1,300 yen on weekends and holidays (550 yen and 650 yen respectively for children). Weekends during the autumn foliage season draw large crowds of both hikers and bathers, so an early morning visit or a weekday trip is recommended. On-site parking for about 90 cars is available free for three hours, though during peak season public transport is the more practical choice.
Quality
Alkaline Simple Hot Spring
Temp
39℃ to 42℃
Supply
Natural Source Flow
Heat
Heated
pH
pH 9.9
0714
AcidicNeutralAlkaline
Use
Stay N/A/Day Trip OK
Fee
Adult 1100JPY/Child 550JPY
Hours
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Hol | |
|---|---|---|---|---|---|---|---|---|
| 08:00 - 22:30 | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ | ◯ |
Summary: What to Know Before Exploring Tokyo's Hot Springs
Tokyo's hot springs fall into three practical groups: the Izu Islands, the western Tama mountains, and the 23 wards.
Izu Islands. Oshima Onsen Hotel, Mamashita Onsen, Shikinejima Mikawawan Kaichu Onsen, Nakanogo Onsen Yasuragi no Yu, Kozushima Onsen Hoyo Center, and Furusato no Yu are all reached by Tokai Kisen ferry from Takeshiba Pier in central Tokyo. Oshima is about 1 hour 45 minutes by jet ferry, Niijima and Shikinejima around 2 hours 20 minutes, and Kozushima, Miyakejima, and Hachijojima anywhere from 4 to 7 hours; budget at least an overnight stay for the farther islands. Small propeller planes from Chofu Airport offer a faster alternative to most islands, though flights are weather-dependent and cancel easily. Kozushima Onsen Hoyo Center's three outdoor baths are mixed-gender and require swimwear, so bring a swimsuit. Shikinejima's cave spring is not a managed facility at all — reaching it means chartering a fishing boat and swimming the final stretch, and only works when a spring tide, low tide, calm sea, and clear weather line up on the same day. Typhoon season (August through October) frequently cancels ferry sailings, so check Tokai Kisen's website shortly before departure rather than relying on the published timetable.
Tama Mountains. Tsurunoyu Onsen (Ogouchiso) is a small, reservation-only inn on the shore of Lake Okutama, about 20-25 minutes by bus from JR Okutama Station; it accepts cash only and closes for winter from December 20 through the end of February. Keio Takaosan Onsen Gokurakuyu sits directly outside the ticket gates of Takaosanguchi Station, making it an easy add-on after a hike up Mount Takao. Both are within two hours of Shinjuku by train, yet offer sharply different experiences — one a secluded mountain retreat, the other a station-front day spa.
23 Wards. Musashi-Koyama Onsen Shimizu-yu and Kamata Onsen are neighborhood sento drawing genuine black-water springs, both within walking distance of train stations on the Tokyu Meguro Line and JR Keihin-Tohoku Line. Shimizu-yu has two separate sources — a 1994 kuroyu well and a 2007 "Golden Spring" well — delivered to a two-tier outdoor bath so visitors can compare both in one visit. Kamata Onsen has operated since 1937 and is known for water dark enough to hide a hand just below the surface; it stays open year-round from 10:00 to 24:00. Admission at both runs around 550 yen, making them an easy, inexpensive stop for anyone with a few hours to spare in the city.
A few points apply across the board. As at most Japanese bathing facilities, visible tattoos may not be permitted; if you have one, contact the facility in advance rather than assume. Cash is the safer default at the smaller island and mountain facilities, even though larger day-spas like Keio Takaosan Onsen Gokurakuyu generally accept cards. Public transport reaches every facility on this list, but island departures run once or twice a day at most, so build in flexibility rather than a tight itinerary — especially if a typhoon or an unfavorable tide is even remotely possible.
The information in this article (admission fees, operating hours, water quality data, etc.) is based on research conducted at the time of writing. Details may have changed or contain errors. Please verify the latest information on each facility's official website or through the local tourism association.
