TransJeju by UTMB
TransJeju by UTMB – Jeju20K
Gasiri Horse Park
Race guide
Updated 18 July 2026
The Jeju20K is the shortest course at TransJeju by UTMB, held on the volcanic island of Jeju off the southern coast of South Korea. Starting and finishing at Gasiri Horse Park, it covers 20 km with a modest 457 m of climbing and a high point of just 466 m, making it the most accessible entry point into the TransJeju weekend. This is a fast, forgiving course by trail-running standards, well suited to newcomers to the sport, runners building toward longer distances, or anyone wanting a taste of Jeju's trails without a full mountain day. The gentle profile and generous four-hour window mean the emphasis here is on enjoying the route and moving steadily rather than surviving big climbs.
The course: a gentle loop from Gasiri Horse Park
The Jeju20K starts at Gasiri Horse Park at 274 m and reaches its only intermediate checkpoint, Deer Mountain, at 12.7 km (298 m) before returning to finish back at Gasiri at 274 m. The course tops out at 466 m, so the total elevation change is spread gently across the distance rather than concentrated in any single steep climb. With just 457 m of gain over 20 km, this is a rolling rather than mountainous course. The start and finish share the same location at the Horse Park, making it straightforward for crew and easy to preview. The long 12.7 km opening leg to Deer Mountain forms the bulk of the outward effort, with a shorter 7.3 km run back to the finish.
How the race unfolds
Because the profile is so gentle, the Jeju20K is less about a decisive climb and more about maintaining a consistent, comfortable pace throughout. The high point of 466 m is reached without any of the sustained ascents that define the longer TransJeju courses, so runners can settle into a steady effort from the start line at Gasiri Horse Park. The natural rhythm of the race is set by the single checkpoint at Deer Mountain at 12.7 km. Reaching that point marks roughly two-thirds of the distance, after which the shorter 7.3 km return leg to the finish gives runners a clear target to push toward. Anyone feeling strong late can pick up the pace on this closing section without fear of a hidden climb ahead.
Pacing and fuelling to the cut-offs
The race has a Saturday 10:00 start, a cut-off at Deer Mountain of 12:20, and a finish cut-off of 14:00, giving a total window of four hours for the 20 km. That is a comfortable limit for the gentle terrain, but the Deer Mountain cut-off at 12:20 leaves 2 hours and 20 minutes to cover the first 12.7 km, so runners should keep moving steadily on the outward leg rather than lingering early. For a race of this length and modest climbing, a light fuelling approach is enough: carry water and a small amount of food to cover the 12.7 km to Deer Mountain, which is the only checkpoint between the start and finish. Both the start and finish at Gasiri Horse Park are crew points, so support and resupply can be arranged there. Focus on staying hydrated across the longer opening leg and you will have plenty in reserve for the run home.
Conditions to expect
Jeju is a volcanic island with a mild, often humid maritime climate, and a mid-morning Saturday start means most of the race is run in daylight during the warmer part of the day. Sun protection and steady hydration are the main considerations; with the finish cut-off at 14:00, there is no need to plan for night running on this course. The terrain around Gasiri Horse Park and Deer Mountain is the gentle, rolling volcanic trail that makes the Jeju20K such an approachable distance. Footing is generally easier than on the high alpine UTMB courses, but Jeju's weather can still bring wind and rain off the sea, so a light windproof layer is sensible. Overall this is a welcoming introduction to trail racing under the UTMB banner, best enjoyed at a relaxed, consistent pace.
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Checkpoints & cut-offs
✓ Course data verified against the official source (2026-07-17) · official source
0 km · 274 m · Sat 10:00
12.7 km · 298 m · Sat 12:20
20 km · 274 m · Sat 14:00
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