Sawatari Hot Springs

Sawatari Hot Springs lie in the upper Agatsuma valley of Gunma Prefecture, a stretch of volcanic highland north of the Shinkansen corridor that has been a destination for onsen travellers from the Edo period through the modern era. The Agatsuma River passes a succession of famous spa towns — Kusatsu, Shima, Manza — and Sawatari occupies a quieter position in this celebrated chain, with a more intimate scale than its well-known neighbours. The valley setting, surrounded by forested ridges, produces a sense of enclosed mountain calm.

The calcium-rich water emerges at a vigorous 55 °C — requiring careful management before entry — with a mildly alkaline pH of 8.1. The high calcium content imparts a dense, mineralised feeling to the water, and the temperature, once adjusted, delivers a deep warming sensation that persists in the body well after the bath. Guests at traditional ryokan in Sawatari typically enjoy multiple short soaks over the course of a stay, following the classic Japanese onsen custom of allowing the mineral-rich water to work gradually over hours and days of rest.