Hallasan National Park (9.6 km), Seokgulam Trail (1.5 km), Gwaneumsa Trail (8.7 km), Donnaeko Trail (7 km), and Eoseungsaengak Trail (1.3 km). The longest trail is Seongpanak Trail which takes about 4.5 hours. Hallasan comprises 153.112 km of the Jeju Island. It rises 1.950 m above the sea level which means the highest mountain in South Korea. This mountain was formed in the fourth Cenozoic era by outburst of volcano. It is mostly composed of basalts. It is extending east and west, and it has high and gradual descent. On the other hand, the south part of the mountain is steep. In the
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