Seth's Fat Ass 50K
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Event overview
Seth’s Fat Ass 50K is scheduled for Saturday, December 20, 2025, in Forest Park, Springfield, MA. The event distance is 50K, organized as up to ten loops of a 5K course. Online registration is handled through UltraSignup and registration closes on December 17. Entry fee is $40, or $45 for late registration, plus UltraSignup fees. Race day registration is available for $45 by cash or card. Each participant will receive event schwag; t-shirts are planned.
Course and logistics
The course consists of ten 5K loops based mostly on the Harrier’s Snow Storm Classic / Bright Nights route. Participants have a seven-hour limit to complete any number of loops and may stop after any loop. The course is not closed to traffic but traffic is expected to be limited; roads should be clean. The start area is in the lot near the baseball fields in Forest Park. Parking is available in the lot near the baseball fields and on North Greeting Road. An additional lot at 245 Park Drive, Longmeadow, MA is not inside Forest Park and requires about a half mile walk to the start. Parking inside Forest Park requires a small fee that is not included with race registration. An athlete guide and prior years’ results are available. Visit the organization's website for the most recent information.