Loaded with major ions — the essential minerals (Ca, Mg).
Buoyancy
Standard buoyancy
LowHigh
Soft water — natural, classic buoyancy.
BicarbonatesSodiumCalcium
Okutama Lake Spa is found in the mountainous Okutama district at the far western edge of Tokyo Metropolis, where bicarbonate thermal waters surface alongside the clear tributaries feeding Okutama Lake within the Chichibu-Tama-Kai National Park. The alkaline mineral composition of these onsen waters is valued for skin-smoothing properties and calming effects on the nervous system, making this a sought-after retreat for Tokyo residents seeking respite in nature. Surrounded by towering cedar and cypress forests, the spa reflects the deep Japanese reverence for natural bathing in landscapes of exceptional scenic beauty and geothermal geological character.
Insider tip — Okutama Lake Spa sits at the far western reach of Tokyo Metropolis, where the Tama River is dammed to form Lake Okutama and bicarbonate spring water at 41°C provides a welcome reward after hiking the Ogouchi and Mitoge ridgelines. The mountain setting feels remote despite being two hours by train from Shinjuku, and autumn foliage in October and November reflects vividly off the lake surface. Early spring visits reveal cherry blossoms framing the forested hillsides visible from the outdoor pools.
