Noma no Yu; Tennen Radon Onsen

Insider tip — Noma no Yu, subtitled Tennen Radon Onsen, draws naturally radon-bearing waters in the Shimokita Peninsula of Aomori, where granitic bedrock dissolves low-level radon into the spring water. The remote Shimokita location, sometimes called the hakoneniwa of Japan, adds an otherworldly, end-of-the-world atmosphere to the bathing experience — an invigorating sense of isolation few onsen can match.