Japanese hot spring (Onsen)
Rokusyaku-oke at Ryokan Sanga, Kurokawa.
An onsen (温泉) is a term for hot springs in the Japanese language, though the term is often used to describe the bathing facilities and inns around the hot springs. As a volcanically active country, Japan has thousands of onsen scattered along its length and breadth. Onsen were traditionally used as public bathing places and today play a central role in directing Japanese domestic tourism.
Onsen by definition use naturally hot water from geothermally heated springs.