小涌谷（こわくだに）、箱根
Kowakudani is a small and scenic resort area nestled in the mountains of Hakone, sitting between the bustling gateway town of Hakone-Yumoto and the higher elevations of Gora. The name literally translates to "small boiling valley," a fitting description for an area defined by its geothermal activity and hot spring culture.
The area sits along the route of the Hakone Tozan Railway, with its own station making it easily accessible as part of the broader Hakone Loop sightseeing circuit. Despite being less visited than neighboring stops, it offers a quieter and more intimate experience of the Hakone mountains.
The most famous attraction in Kowakudani is Yunessun, a large and unique onsen theme park that combines traditional hot spring bathing with resort-style entertainment. It is one of the most unusual spa facilities in Japan, featuring themed pools including baths infused with red wine, green tea, sake, and coffee.
Yunessun operates two distinct sections. The themed pool area requires a swimsuit and is family-friendly, while the separate Mori no Yu section is a more traditional nude bathing facility with indoor and outdoor baths set within a forested hillside environment. Together, they attract visitors of all ages and travel styles.
The surrounding forest and hillside landscape of Kowakudani is particularly beautiful during autumn, when the dense woodland turns vivid shades of red and gold. The area receives fewer visitors than the more famous spots in Hakone, giving it a noticeably more peaceful atmosphere.
Several high-quality ryokan and resort hotels are located in and around Kowakudani, many offering private onsen facilities and kaiseki dining. The relative seclusion of the area makes it a preferred choice for travelers seeking a quieter and more restorative Hakone experience away from the busier tourist centers.
The hot spring waters of Kowakudani are rich in sulfur and sodium bicarbonate, known for their beneficial effects on skin and circulation. The waters flow naturally from the same geothermal sources that feed the wider Hakone hot spring network.
The area is also within comfortable walking or cycling distance of Hakone Open-Air Museum at the neighboring Chokoku-no-Mori Station, Japan's first open-air art museum displaying sculptures by Henry Moore, Rodin, and Picasso across sweeping landscaped grounds.
Kowakudani sits on the Hakone Tozan Railway line and is served by Kowakidani Station, one stop below Gora on the mountain railway. From Hakone-Yumoto, the journey takes approximately 30 minutes through some of the most scenic forested mountain terrain on the entire route.
Visitors arriving from Tokyo can reach the area most conveniently via the Odakyu Romancecar limited express to Hakone-Yumoto, followed by the mountain railway connection. The Hakone Free Pass covers all transport along this route and is strongly recommended for visitors planning a full day of sightseeing across the region.