Mizunashikaihin Hot Spring

Mizunashi Kaihin is an extraordinary tidal onsen on the Hokkaido coast near Hakodate, four outdoor pools of bicarbonate spring water separated from the Pacific Ocean by nothing but a low rock wall, usable only around low tide. The temperature shifts as sea water seeps through the cracks, so you move between pools to find your comfort zone. One of those places that makes you feel like you found a secret.