Seth's Fat Ass 50K
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Event details
Seth’s Fat Ass 50K takes place on Saturday, December 20, 2025, at Forest Park in Springfield, MA. Entry fees are $40 or $45 for late registration, plus UltraSignup fees. Online registration is available via UltraSignup. Race day registration is available for $45 by cash or card. A paper registration form for race day is noted as coming soon. The 2024 Athlete Guide is available and a 2025 guide is listed as coming soon.
Course and logistics
The course is ten loops of the Harrier’s Snow Storm Classic 5K route, largely following the Bright Nights route. Runners have seven hours to complete one, two, three or all ten 5K loops. The course is on roads that should be clean and is not closed to traffic, though traffic is expected to be limited. The start area is in the lot near the baseball fields.
Distances:
- 50 km total (ten 5K loops)
- Single 5K loop options available
Parking is available in the lot near the baseball fields and on North Greeting Road. Additional parking at 245 Park Drive, Longmeadow is not inside Forest Park and is about a half mile walk to the start. Parking within Forest Park may require a small fee that is not included with race registration, and a parking attendant may be present at the Sumner Avenue entrance. Visit the organization's website for the most recent information.