Ulleungdo, also spelled Ulreungdo, is a South Korean island 120 kilometres east of the Korean Peninsula in the Sea of Japan. It was formerly known as Dagelet Island or Argonaut Island in Europe. Volcanic in origin, the rocky steep-sided island is the top of a large stratovolcano which rises from the seafloor, reaching a maximum elevation of 984 metres (3,228 ft) at Seonginbong Peak. The island is 9.5 kilometres (6 mi) in length and ten kilometres (6 mi) in width; it has an area of 72.86 km2 (28.13 sq mi). It has a population of 10,426 inhabitants.