South Korea

At the top of the Hallasan volcano, in the crater, there is Lake Baengnokdam, which expands and evaporates depending on rainfall.

An excerpt from the article 15 facts about South Korea

It can reach a diameter of 2 kilometers and a depth of up to 100 meters. The slopes of Hallasan are covered with many smaller cones that once released lava and pyroclastic material. Such small cones on the slopes of a large volcano are called parasitic cones.