Grotte du Mammoth 50K/25K

Grotte du Mammoth 50K/25K is a trail race held in Park City, Kentucky, on October 24, 2026, close to Mammoth Cave National Park. Two distances are offered — a 25K (15.5 miles) and a 50K (31 miles) — both run on forest trails through the wooded country around the park.

The 50K is the headline event and asks for genuine endurance over varied natural terrain rather than road speed. Build over four to five months with a weekend long run of three hours or more, ideally on trails, and get used to eating while moving, since most first ultras come apart on fueling rather than fitness. The 25K is a far more approachable way to see the same ground: if you have run a half marathon you can finish it, though it will take longer than the distance suggests. Trail shoes and a way of carrying water are worth having for either.