Marunuma Onsen

Marunuma Onsen—Round Marsh Spring—is one of the four springs of the Katashina Onsenkyo cluster in Katashina Village, Gunma Prefecture, its name evoking the round, bowl-shaped wetland basins that form in volcanic highland terrain where subsidence or crater geology creates the circular marsh features characteristic of Gunma's most geologically active mountain landscapes. The bicarbonate and carbonated waters deliver the effervescent mineral soak typical of Gunma's volcanic highland springs, where natural CO2 adds stimulating tactile quality to the gentle alkaline warmth of bicarbonate mineral waters drawn from the geologically complex substrate beneath the highland marshland landscape. The four-spring cluster of Katashina Onsenkyo gives Marunuma a communal thermal setting where multiple mineral water sources serve a concentrated high-altitude area of exceptional natural beauty.