Ushiohara Onsen

Kitahiroshima, Hiroshima, Japan

Location: Kitahiroshima, Hiroshima, Japan
Water type: sodium chloride
Temperature: 41 °C
pH: 7.3

Water profile

Thermicity

Sedative

41 °C

LowHigh

Relaxing — deep, immediate muscle release.

Mineralisation

Restorative

LowHigh

Loaded with major ions — the essential minerals (Ca, Mg).

Buoyancy

Effortless float

LowHigh

Dense, salty water — you float without effort.

SodiumChloruresBrome

Ushiohara Onsen is an iodine-rich thermal spring in Hiroshima Prefecture, its mineral-bearing waters carrying the coastal sedimentary character typical of iodine springs found near ancient sea-bottom geological formations, delivering the antibacterial and skin-conditioning mineral benefits that have made iodine springs valued across Japan's coastal and lowland thermal bathing tradition. The name—Tidewaters Plain—evokes a landscape shaped by the historical action of the inland Seto Sea tides, connecting the spring's mineral character to the marine heritage of a prefecture whose coastline has been defined for millennia by the tidal rhythms of Japan's most famously beautiful inland sea. This spring's iodine mineral profile and coastal name connect Hiroshima's thermal tradition to the maritime geological heritage of the Seto Inland Sea landscape.

Insider tip — Ushiohara Onsen draws iodine-rich sodium-chloride waters from deep sedimentary layers beneath the central Hiroshima highlands, giving baths a slightly saline character that warms the body long after leaving the tub. The surrounding Sandankyo gorge area, a protected scenic zone, draws hikers and kayakers who appreciate the remote mountain setting. Facilities are modest and community-focused, with a loyal clientele of local farmers and forestry workers. The waters are said to be particularly effective for joint pain and fatigue.

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