# 2026 Forest Park Winter Marathon
_2026森林公園ウインターマラソン_

- **When:** Sat, Dec 5, 2026 (JST)
- **Where:** 国営武蔵丘陵森林公園「運動広場」 — 埼玉県 比企郡滑川町 比企郡滑川町大字山田1920
- **Price:** price on the official site
- **Category:** Sports & Competitions
- **Official site:** https://up-run.jp/events/up-shinrinkoen1/
- **On Tokyo Events:** https://eventstokyo.com/en/events/2026-forest-park-winter-marathon

![](https://up-run.jp/ogp.jpg)

Held in the National Musashi Kyuryo Forest Park, this marathon takes place on a scenic, challenging course surrounded by lush nature. With steep slopes reaching up to 27%, it's a popular training ground for serious athletes. Participants run loops of 5 km, making it a suitable event both for experienced runners aiming for new personal bests and for beginners seeking practice. Official timekeeping is provided, so those interested in tracking their performance are welcome to join.

---
Source: Tokyo Events — https://eventstokyo.com/en/events/2026-forest-park-winter-marathon