Rich in active gases or metals — a strong mineral character.
Buoyancy
Standard buoyancy
LowHigh
Soft water — natural, classic buoyancy.
SoufreSulfuresSulfates
On Yakushima island, the sulfurous Yumugi hot spring forms an open-air pool set right into the rock, in the tradition of Japan's wild bathing spots. A simple, rustic setting valued for its unspoiled natural surroundings.
Insider tip — Yumugi Hot Spring is a sulfurous spring on Yakushima (Kagoshima), an island inscribed as a UNESCO World Heritage Site for its thousand-year-old cedar forests (yakusugi, > 1,000 years old). Yakushima has several spectacular natural onsen — including the famous Hirauchi Kaichu Onsen, accessible only at low tide among the rocks of the wild coast.