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
Sousaki volcano Sousaki volcano Sousaki () is an extinct volcano and modern solfatara field in northeastern Corinthia, Greece, at the northwest end of the Aegean volcanic arc. The volcano was active 4.0 to 2.3 million years ago, during the Pliocene and early Quaternary periods of the Earth's geological history. There is still significant solfataric activity at this location. The volcano erupted dacite lava. The geothermal system releases about 1 megagram per day of gases at 42 °C, 90% CO and < 1% each of CH and HS. The earthquakes of 1997 of 3-4 R had as a result the uprising magma in