Ogawa Onsen is located in the upstream gorge of the Ogawa River in the mountains of Asahi Town, Shimoniikawa District, Toyama Prefecture. This renowned hot spring has a history of over 400 years, having been discovered in 1617. Counted among the Four Famous Hot Springs of Etchu, it has long been cherished as a "hot spring for fertility" and a "therapeutic hot spring." Hotel Ogawa, established in 1886, and its therapeutic bathing facility Furokan stand at the end of a long tunnel, offering the ultimate sense of privacy as a secluded mountain inn.

The most distinctive feature of this hot spring is the natural cave open-air bath, designated as a natural monument, formed by the solidification of hot spring deposits. Located about 750 meters (7-8 minutes walk) from the inn, this cave bath offers the quintessential secret hot spring experience, allowing visitors to enjoy bathing in complete nature. Nearby is "Renge-no-yu," a women-only open-air bath where bathers can enjoy views of mountain streams and surrounding peaks. Within the facility, there are five distinctive bathing areas including separate gender large communal baths, a 3-meter diameter hinoki cypress barrel open-air bath, and rock open-air baths.

The spring quality is sodium-chloride/hydrogen carbonate spring, a relatively rare hydrogen carbonate spring in the prefecture. The 100% free-flowing spring water boasts an abundant flow rate of 400-470 liters per minute and is provided without dilution or heating. The hydrogen carbonate spring has the characteristic soft and smooth texture, known as a "beautiful skin hot spring," with properties that warm the body from its core. The spring water is also potable and is used in cooking rice for kamameshi and breakfast porridge, adding a subtle salty flavor that enhances the dishes.

This hot spring has historical significance, having been featured in Kyoka Izumi's novel "Yujo no Tamashii" and visited by artist Yumeji Takehisa for a month-long stay, attracting many cultural figures over the years. Surrounded by the soothing sounds of mountain streams, bird songs, and the Northern Alps mountains, the area offers wild vegetables in spring and mushrooms in autumn. Moreover, due to its proximity to the sea, visitors can enjoy fresh seafood from Toyama Bay (white shrimp, firefly squid, yellowtail, snow crab, etc.), making it a rare hot spring destination where both mountain and sea delicacies can be savored. During the autumn foliage season (mid-October to mid-November), visitors can also enjoy spectacular views of the surrounding mountains painted in a mosaic of colors.