Mizunashi Seaside Hot Spring (tidal open-air bath) 水無海浜温泉

Mizunashikaihin Hot Spring is a rare onsen located in an inlet of Cape Esan, at the foot of the active volcano Esan. The temperature of the bath is naturally regulated by the tides, and it can become submerged at high tide or too hot at low tide, earning it the nickname "phantom onsen." There is no fee to enter, and a free parking lot is available.

Source: city.hakodate.hokkaido.jp ↗, read 2026-09-11