An Explosion Without a Mountain
Sangumburi Crater is a geological anomaly on an island of volcanoes. Unlike the conical peaks that dominate Jeju's landscape, Sangumburi is a vast, bowl-shaped depression punched into the earth. It is a maar volcano, the result of a phreatomagmatic eruption—a violent, explosive event that occurs when rising magma meets groundwater. The resulting steam explosion blasted a wide crater instead of building a tall cone with lava flows. This process left a massive cavity with a circumference of 2,070 meters and a diameter of about 650 meters. The crater floor sits roughly 100 meters below the rim.
The scale of the crater is immense; its internal area covers 300,000 square meters. Designated as South Korea's Natural Monument No. 263, Sangumburi is the only maar-type crater on the island and one of only a few in the world that is not filled with water. Its dry condition is due to the porous basalt gravel of the crater walls, which allows water to drain away. This unique geology allows for direct observation of the crater floor and the distinct ecosystems that have formed within it. Visitors are not permitted inside the crater itself to preserve its scientific value, but well-maintained paths along the rim provide panoramic views.