Onsen

Japanese ledy in onsen
© 2005 - Jason Weddington
https://www.flickr.com/photos/jwedd459/11683831443/

An onsen 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 come in many types and shapes, including outdoor  roten-buro or noten-buro?) and indoor baths. Baths may be either public run by a municipality or private ( uchiyu?) often run as part of a hotel, ryokan or bed and breakfast ( minshuku?).
http://en.wikipedia.org/wiki/Onsen