Jeju Island is the southern-most point of the Republic of Korea. It is an ellipsoid with the major axis lying southwest-northeast, with its area 183,160 ha. Volcanic activities within the Jeju Volcano began at the end of the Tertiary Period at a hot spot on the sea bottom.
The island gradually reached sea level as a result of volcanic activities that began approximately 1.2 million years ago. In the center of the island, Hallasan Mountain rises 1,950 meters above sea level. The World Natural Heritage in Jeju consists of three sites covering a total of 188.4 square kilometers, which is 10.1 percent of the island’s total territory, and 1.2 square kilometers of publicly owned water surface. Hallasan Mountain has a vast array of plant and animal species and superb natural scenery that features the crater lake Baengnokdam (White Deer Lake) on the top, fantastic cliffs and waterfalls. The mountain has a unique vertical distribution of plants of diverse zones ranging from the subtropical, warm temperate and temperate to frigid zones.
The Seongsan Ilchulbong Tuff Cone, created by undersea volcanic eruptions, offers a dramatic landscape. The fortress-like peak, with its walls rising out of the ocean, has exceptional exposures of its structural and sediment characteristics, including the crater preserving its original shape.
The Geomunoreum Lava Tube System, regarded as the finest of its kind in the world, comprises a lateral volcano and five lava caves. They were created some 100,000-300,000 years ago when magma erupted from Geomunoreum and flowed through natural conduits slanted northeast toward the coastline, which are now empty caves displaying unique spectacles of multicolored carbonate roofs and floors. Varying in length, structure and component, the five caves are Bengdwigul Cave, Manjanggul Cave, Gimnyeonggul Cave, Yongcheongul Cave and Dangcheomulgul Cave.