Renge Onsen Hakubadake Renge Onsen Lodge is a solitary mountain lodge known as a "cloud-top secret hot spring," located at an elevation of 1,475 meters at the foot of Mt. Hakuba in the Northern Alps, Itoigawa City, Niigata Prefecture. It serves as a climbing entrance to the Northern Alps from the Niigata side and is used by many climbers. The operating period is seasonal, from mid-March to around October 20.

The main feature is four outdoor wild baths (notenбuro), each with different spring qualities, which visitors can tour by walking along mountain trails:

1. **Senki-no-yu**: Simple acidic spring (pH 2.8, source temperature 79°C)

2. **Kogane-no-yu**: Magnesium bicarbonate spring

3. **Yakushi-no-yu**: Simple sulfur spring / acidic sulfate spring

4. **Sangokuichi-no-yu**: Acidic aluminum sulfate spring

The four outdoor baths are open-air baths where you can bathe in the midst of nature. Each bath has different spring qualities, with varying colors, scents, and textures. The wild and rustic atmosphere offers the true essence of secret hot springs.

The lodge also has an indoor bath called "Souyu" (communal bath), which is a simple hot spring (hypotonic, weakly acidic, high-temperature spring). Day-use bathing is available: indoor + outdoor baths set for adults 800 yen / children 500 yen, outdoor baths only for adults 500 yen / children 200 yen, indoor bath only for adults 800 yen / children 500 yen. Operating hours are 9:30-17:00.

Accommodation is by complete reservation, starting from 13,000 yen per night with two meals, or from 7,000 yen for room only. Private rooms (for 1-4 people) require an additional 3,000 yen per room. The breakfast bean curry is popular, with its gentle flavor favored by climbers. A point card system is available: 1 point per stay, 10 points for 1 free night.

Access: 1 hour 35 minutes by bus from Hokuriku Shinkansen Itoigawa Station, or about 1 hour by bus from JR Oito Line Hiraiwa Station. Buses run 4 times daily from mid-July to mid-October (advance confirmation required). By car, it's over 1.5 hours from Itoigawa IC, with about 21 km of forest road (many curves) from near Hiraiwa Station. Renge Onsen parking lot (free, about 70 spaces) is available, but may fill early in the morning on August weekends.

The climbing route to Mt. Hakuba is 9.3 km one way with 1,357m elevation gain, taking about 7 hours ascending and 5.5 hours descending. It's an ideal base for mountain trips combining climbing and hot springs, a famous hot spring in the Northern Alps.