TransJeju by UTMB Jeju100M

Jeju100M is TransJeju's longest race and a broad crossing of the island's volcanic interior. It starts at Jeju World Cup Stadium at night, climbs through dark forest toward Mount Halla, and returns to Seogwipo after a full mountain circuit. The long cutoff still demands steady progress through an overnight start and a second day outside.

The route covers 148 kilometers and gains about 5,000 meters. Its defining feature is the climb over Mount Halla, supported by long forest approaches, volcanic trail, and extended descents toward Seogwipo. Trekking poles are not allowed, so runners must manage the climbing and technical footing without them.

Jeju's early autumn lowlands are often mild, but rain and wind remain possible. Conditions on Mount Halla can be much colder and more exposed than at the stadium, particularly during the overnight climb. Runners should plan for damp trail, changing visibility, and a meaningful temperature difference between coast and summit.