Kaminoko Pond, Artificial pond in Kiyosato, Japan.

Kaminoko Pond lies in forest on the northern outer rim of the Lake Mashu caldera in Kiyosato, Hokkaido, and measures about 220 metres around. Its roughly five-metre depth and high clarity let sunlight reach the white volcanic ash on the bottom, giving the water a blue cast. Fallen trees lie intact on the pond bed, and no surface stream flows in; the water leaves via the Satsutsu River toward the Shari River.

The pond drew its name from ancient Ainu traditions suggesting its waters flow from the sacred Lake Mashu through underground channels. This connection with the larger lake has shaped how people have understood the site for generations.

The pond's name comes from the Ainu word Kamuy-to, their name for Lake Mashu, meaning 'lake of the gods'; Kaminoko thus means 'child of the gods'. The Ainu believed the pond's water seeped underground from Lake Mashu. Water quality surveys later showed the source is rain falling on the crater rim, not the lake itself.

Access to the pond is by an unpaved road of about two kilometers, with parking for around thirty cars nearby. Sturdy footwear helps on muddy or wet sections of the approach.

The pond's blue colour comes from sunlight reaching the white volcanic ash on the bottom through highly transparent water about five metres deep. The surrounding crater rim of Lake Mashu feeds it with about 12,000 tonnes of spring water a day, and the pond never freezes, even in winter.