 The dormant shield volcano Hallasan, 1950 m high, occupies most of Jeju Island. |
 On the summit of Hallasan volcano there is a 400 m wide crater with lake inside. |
 On the slopes of Hallasan volcano there are about 360 scoria cones of Pleistocene-Holocene age. |
 Ilchulbong (‘Sunrise Peak’) tuff cone, 180 m high, was formed by hydrovolcanic eruptions in the shallow sea about 5000 years ago. |
 The Manjanggul Lava tube is up to 30 m high and 9 km long. Inside the tube there are lava stalactites, stalagmites, ropy lava and so on. |
 Songaksan tuff ring was erupted 3.7 ka BP in a coastal setting. |