Jeju Island

Jejudo (also known as Jeju Island) is the largest island off the coast of the Korean Peninsula. It is the main island of Jeju Province of South Korea. The island lies in the Korea Strait, southwest of South Jeolla Province. The island contains the natural World Heritage Site Jeju Volcanic Island and Lava Tubes. The highest point in South Korea is the Island's dormant volcano, Hallasan, which stands above sea level. Jejudo has a temperate climate. Even in winter, the temperature rarely falls below . The Island is a popular place for Korean newlyweds to honeymoon.
Jeju Island is 73 km wide from east to west and 31 km wide from north to south. Most of Jeju Island is made out of volcanic rocks from the Holocene era.
First, the basalt lava erupted to make the Hallasan shield volcano about 2 million years ago. Hallasan was still active into recorded history, but it is not active now. Then this first layer of volcanic rock was covered up with sediment. Then there was another set of eruptions, which made most of the rock on the surface of Jeju Island today. In the third round of volcanic activity, Hallasan grew to its current, tall height, 1950 m.