Lake Unagi (鰻池, Unagi ike) is a Japanese maar lake associated with an eruptive vent line extending towards the sea from the parent volcano Ikeda Caldera which contains Lake Ikeda (池田湖, Ikeda-ko).

It is located within the city limits of Ibusuki, Kagoshima on Kyūshū island, Japan, and there are associated hot springs.

[3] Lake Unagi is within the larger and older Ata Caldera and technically its water fills in Unagi maar.

Shortly after the Ikeda Caldera forming eruption of 4800 years ago[4] a fissure vent line southeast of the caldera evolved that produced the maar eruption that formed Lake Unagi and then the pumiceous Yamagawa base surge.

[5] Ikezoko maar is more proximal in the vent line from the Ikeda Caldera to the north.