Katase Onsen

Izu, Shizuoka, Japan

Location: Izu, Shizuoka, Japan
Water type: sodium chloride
Temperature: 42 °C
pH: 7.3

Water profile

Thermicity

Sedative

42 °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

Katase Onsen lies along the East Izu coastline of Shizuoka Prefecture, historically known as Minami-Atakawa (South Atakawa) before adopting its current name, situated between the thermal resort communities of Shirata and Atakawa along one of Japan's most densely spring-rich Pacific coastlines above the sea cliffs. The iodine-rich waters carry the coastal sedimentary mineral character of the East Izu peninsula, where ancient marine geology concentrates iodine compounds in the groundwater feeding numerous springs along the clifftop shoreline. Katase represents the small-scale, community-rooted character of the smaller East Izu resorts that complement the region's famous larger thermal destinations with an intimate, unhurried bathing experience.

Insider tip — Katase Onsen is nestled on the eastern Izu Peninsula coast in Shizuoka, where iodine-rich sodium-chloride waters emerge near the Pacific shoreline at around 42°C. The salt-laden spring warms the body deeply and leaves skin with a distinctive silky film long after bathing. Many establishments here offer ocean-view baths overlooking Sagami Bay, with Oshima island visible on clear days. This coastal onsen is popular with Tokyo day-trippers seeking both the mineral bath and fresh seafood from local fishing boats.

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