Life's Best Moments: Onsen or hot springs are a popular form of recreation in Japan . As a volcanically active country, Japan has thousands of onsen on its islands. They were traditionally used as public bathing places and still are today though most people have efficient baths in their homes. Onsen come in many types and shapes, including outdoor rotenburo or notenburo and indoor baths. Baths are often run as part of a hotel, ryokan, minshuku or Japanese inn.