TransJeju by UTMB® 2026

When you say "Jeju" to someone who doesn’t know it, either they shrug, or they reply "it’s the Korean Corsica, right?" 🤷. So this is your moment to explain what this island really is 🫵.

A volcano that rose out of the ocean two million years ago, listed three times by UNESCO, with a crater lake at the top of its mountain, some of the world’s most beautiful underground lava tubes, and biodiversity that runs from subtropical forest at the bottom all the way up to subarctic vegetation at the top 🌳. TransJeju by UTMB takes place in exactly that kind of place 🌋.

What makes Jeju truly unique on this planet is that it’s the only place in the world where all four types of international recognition coexist in the same spot: a UNESCO World Heritage Site, a Biosphere Reserve, a UNESCO Global Geopark, and two Ramsar wetlands. Four labels is no small thing. The UNESCO site includes three components: the lava tube system of Geomunoreum, considered the best cave system of its kind in the world, the Seongsan Ilchulbong cone, and Mount Hallasan, the highest in South Korea, with its waterfalls, rock formations, and a crater filled with a lake 🛶. That’s all... 😮So on the same course, you go from the warm coastal forest to the almost alpine slopes near the summit 🏔️. Fun fact: at the top of Hallasan grows the world’s largest forest of Abies koreana: the Korean fir, which has become popular worldwide as a Christmas tree 🎄. So at one point in the race, you’re running through the largest Christmas-tree forest in the world. If you’re wearing a red jacket (and a silky silver beard), you’ll absolutely crush it in the photos 🧑‍🎄.

There are four formats on offer, covering the full spectrum of what a volcanic island can reasonably make you endure 😬. The flagship event, the ultratrail of ultratrails, the crème de la crème, the "Jeju100M", is the monster of the lineup 👑: 148 km and 5,000 m of elevation gain, with 4 Running Stones for UTMB qualifications in Chamonix 🏔️. Start from Seogwipo, the island’s second city, set on the south coast. The "Jeju100K" offers 104 km and 4,000 m D+, which is already a solid chunk, including the climb of Hallasan and the passage by the crater lake of Baekrokdam at the summit 🔝. The 100K runners climb Hallasan at sunset 🌄, which the race director describes as "very special". "Very special" is the Korean understatement for "you’re going to get a sunset photo on top of a UNESCO-listed volcano that you’ll keep as your wallpaper for at least two years" 📸. The "Jeju60K" offers 60 km and 1,400 m D+. Note that the elevation drops significantly, reflecting the more coastal profile of this format. Finally, the "Jeju20K" with 508 m D+ is the perfect introduction to sample the terrain without committing all your physical and mental reserves 🤯.

What makes TransJeju stand out in the landscape of major Asian races on the UTMB circuit is a combination you won’t find elsewhere. First, islandness: you’re running on an island, which mechanically creates an intimacy with the terrain that continental races don’t have 🏝️. No theoretical escape route, no distant horizon toward another range: you’re on the island, in the island, you’re almost... the island 😂. Next, verticality: starting from the seaside and climbing to 1,950 meters before descending on the other side is a full traverse that tells the whole geology of the place in order. And finally, the crater lake of Baekrokdam and Youngsil Giam (a cliff made up of rocks with strange shapes) are checkpoints that exist in no other race in the world. That’s what a race with an identity looks like 🌊.

The host city, Seogwipo, also deserves a few words. The island’s second city, set on the south coast facing the East China Sea, it’s known for its waterfalls that drop straight into the ocean: the Jeongbang Falls, the only ones in East Asia to fall directly into the sea, and for its seafood markets that the race director himself enthusiastically promotes. Yes, Byeungsik Ahn wants participants and families to enjoy the local seafood specialties before and after the race. A race director who sells you the feats of the haenyeo (Jeju’s traditional women divers who have been free-diving for centuries) and the coast’s restaurants at the same time as his course marking. We love this man 🦞.

The next edition will take place in autumn 🍂. October in Jeju is Korean autumn at its finest: mild temperatures, the Hallasan forests starting to turn red and orange 🧡, and an end-of-day light over the Pacific that alone justifies the plane ticket ✈️. If you’ve never run in Korea, never set foot on a volcanic island of this caliber, and never had makgeolli around a table of international trail runners after a race, now’s the time to fix that.

The volcano is waiting for you 🌋, and so is your bib!