Mt. Hallasan in Jeju island, the highest mountain in South Korea (6,388 ft)

Hallasan is a massive shield volcano which forms the bulk of Jeju Island and is often taken as representing the island itself. There is a Korean traditional local saying that "Jeju Island is Hallasan, and Hallasan is Jeju." The mountain can indeed be seen from all places on the island, but its peak is often covered in clouds. There is a crater lake on Hallasan called Baengnokdam (백록담; 白鹿潭), meaning "white deer lake". It is formed by the collapse of the top of the ridge by the movement of magma underground.[12] There is a legend attributing the name of the lake to otherworldly men who descend from heaven to play with white deer. Depending on the season, the circumference of the lake is up to 2 kilometres (1.2 mi) with a depth up to about 100 metres (330 ft).