Due to the small surface area to depth ratio, the water temperature remains quite constant throughout the year, making it the northernmost ice-free lake in Japan.

[3] According to the Global Volcanism Program, the caldera was formed 31 to 34 thousand years ago by one of Hokkaidō's largest quaternary eruptions.

[3] The name of Lake Shikotsu derives from the Ainu language shikot, meaning big depression or hollow.

To the Japanese, this sounded too much like dead bones (死骨, shikotsu), so they attempted to rename it engi, but this name did not stick.

National Highway 276 runs along the southern bank, connecting the lake with Tomakomai and Date.