Hallasan comprises 153.112 km2 of Jeju Island. It rises 1,950 m above sea level, which means that it is the highest mountain in South Korea. This mountain was formed in the fourth Cenozoic era by the eruption of a volcano. It is mostly composed of basalts. It extends east and west, and it has high and gradual ascent. On the other hand, the south part of the mountain is steep. In the summit, there is a crater lake called "Baekrokdam". Since the mountain has high altitude, there are a number of alpine plants and animals. 1,800 kinds of plants, including 400 kinds of specimen plants and 50 kinds of special plants, exist in Hallasan. Jeju island was designated as a
Biosphere Reserve in 2002 and Hallasan National Park is one of the regions of Jeju Biosphere. ==References==