Distance
Start Time
Cutoff
Terrain
This seaside event is staged in a park that reaches out into Tokyo Bay, with water on every side and a course that stays completely flat from the first step to the last. Runners choose between a half marathon, a 21km relay, 10km, 5km, a 2.5km mini marathon, a 2.5km parent-child pair race and a 400m challenge run, so the day works just as well for serious racers as it does for families. Shopping centres and entertainment facilities sit within easy reach of the park, making it simple to turn race day into an afternoon of sightseeing. Early October in Koto is mild and settled, with average highs near 23°C, which makes for comfortable running conditions.
Park surrounded by water on all sides
Completely flat course with no elevation change
Tokyo Bay waterfront setting
Shopping centres and entertainment venues close to the park
Something for every age, from a 400m challenge run to a half marathon
Start / Finish
Park on the Toyosu waterfront in Koto, Tokyo, on a spit of land jutting into Tokyo Bay
Same waterfront park area as the start
Terrain
Route
Getting There
On the day
Before you enter
Other questions
The race is held on Saturday 3 October 2026 in Koto, Tokyo, in a park on the Toyosu waterfront that juts out into Tokyo Bay.
Not at all. The course is described as completely flat with no elevation change, running through a park that is surrounded by water on all sides.
Teams cover 21km between them and the entry fee of ¥3,600 is charged per team member rather than per team.
Early October averages in Koto sit around 15.5°C to 22.6°C, with roughly 6 hours 54 minutes of sunshine a day, light rainfall of about 4.3 mm and a moderate UV index of 4.0. Sunrise is around 05:47 and sunset around 17:04.
There are plenty of shopping centres and entertainment facilities close to the park, so runners and spectators can sightsee or shop around the Toyosu area after the race.
Entry fee
Registration isn't open yet. We'll show pricing when the organiser confirms.Koto, Japan
Expected October 2027
Provisional date, around Oct 2Are you the organiser of 12th Toyosu Seaside Marathon (第12回 豊洲のうみべマラソン)?
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