The Seoul 100K is an unparalleled ultra trail running adventure that immerses participants in the captivating fusion of nature and urban life unique to South Korea's bustling capital. As the sole international ultramarathon of its kind, this race offers a rare glimpse into Seoul’s diverse terrain and cultural heritage. Starting early on a crisp morning, runners begin their journey through Bukhansan National Park, where verdant forests and rugged mountain trails provide both challenge and respite from the city's energy. The route then winds down to traverse the Han River, offering panoramic views of bustling metropolises and historic landmarks that dot the riverbanks. As daylight fades into evening, runners continue along scenic roads encircling Seoul’s urban core, where towering skyscrapers contrast with ancient temples and palaces. This dynamic backdrop sets a stage for an unforgettable marathon experience, blending modern city life with centuries-old traditions. Throughout the course, participants will encounter various checkpoints that cater to their needs, ensuring they can focus on enjoying every step of this epic journey through Seoul’s breathtaking landscapes and vibrant neighborhoods. The race culminates in a celebration of resilience and camaraderie among runners who have pushed themselves beyond limits set by city confines, discovering new perspectives on the interplay between nature and urbanity. This event is more than just an athletic challenge; it's an opportunity to explore Seoul like never before—where every kilometer reveals a unique story waiting to be told.
Races Offered
100K trail (only runners outside S. Korea)
Sep 20, 2026
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Distance —
104K
terrain
Type —
Running
timer
72 days remaining
sell
$280.46
20K trail (only runners outside S. Korea)
Sep 20, 2026
straighten
Distance —
23.4K
terrain
Type —
Running
timer
72 days remaining
sell
$110.59
50K trail (only runners outside S. Korea)
Sep 20, 2026
straighten
Distance —
51.5K
terrain
Type —
Running
timer
72 days remaining
sell
$190.40
Weather History
These values represent the 3-year monthly averages for September in Seoul.
thermostatTemperature
19.3° / 26.6°
wb_sunnyFeels like
20.6° / 28.5°
light_mode
Avg sunshine hours
7h 53m
water_drop
Avg rainfall
7.3 mm
ac_unit
Avg snowfall
—
air
Avg wind speed
7.3 km/h (Light breeze)
opacity
Sweat loss rate
High
terrain
Course conditions
Hard and dry surface
sunny
Max UV Index
Moderate (5.0)
humidity_mid
Humidity
81.1%
wb_twilight
Sunrise
06:13
nightlight
Sunset
18:39
About Seoul
Learn more about the host city, Seoul.
Seoul (서울) is the capital of South Korea. With a population of over 9 million, Seoul is by far South Korea's largest city and one of East Asia's financial and cultural centers. A fascinating blend of ancient traditions and cutting-edge digital technology, home to endless street food vendors and vast nightlife districts, an extraordinarily high-pressure educational system and serene Buddhist temples, a dynamic trend-setting youth culture and often crushing conformism, extraordinary architecture and endless monotonous rows of grey apartment buildings, Seoul is a city filled with stark contrasts, contradictions, and paradoxes. People in Seoul can enjoy various artistic activities such as plays, musicals, and concerts.