trailmarkNational Parks passport

U.S. NATIONAL PARK · EST. 1941

Mammoth Cave

KY

The longest known cave system on Earth, beneath rolling Kentucky forest.

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Trail series Mammoth Cave counts toward one named set on Trailmark: The Underground Three. Finish a set and it stamps complete on your map.

Mammoth Cave is one of the 63 U.S. National Parks — first designated in 1941, in KY. Been there? Tap it onto your Trailmark map and watch your collection, progress ring and percentile grow. Free, for fun — your map saves and keeps growing trip after trip.