South Korea most of which is not arable. Lowlands, located primarily in the west and southeast, make up only 30% of the total land area. About three thousand islands, mostly small and uninhabited, lie off the western and southern coasts of South Korea. Jeju-do is about off the southern coast of South Korea. It is the country's largest island, with an area of . Jeju is also the site of South Korea's highest point: Hallasan, an extinct volcano, reaches above sea level. The easternmost islands of South Korea include Ulleungdo and Liancourt Rocks (Dokdo/Takeshima), while Marado and Socotra Rock are the southernmost
Jeju Volcanic Island and Lava Tubes lasted until the early Tertiary period. The most recent eruptions are estimated to be about 5,000 years ago, which puts the volcano into the active classification, meaning eruptions in the last 10,000 years. The designation as active is not agreed by all, as more monitoring and study are needed to better understand the volcano. The island is covered in volcanic rock and volcanic soil produced by Hallasan (Hangul: 한라산). Baengnokdam (Hangul: 백록담), the crater, and lake in it are located at the peak of Hallasan, which was formed over 25,000 years ago. Jeju is scientifically valuable for its extensive system