Mammoth Cave National Park · caps RVs at 40 ft

The world's longest known cave system runs 426+ mapped miles directly under the park, and ranger-led tours are the only legal way in — every RV trip planning starts with the tour-reservation calendar, not the campsite calendar. Mammoth Cave Campground (the main developed loop) accepts rigs up to 40 ft, runs dry-camp only, March through November. Houchin Ferry Campground on the Green River is dry-camp with a 30-ft cap. Maple Springs Group Camp can take larger RVs for organized groups. No hookups anywhere inside the park; dump station opens with the main campground season. The Green River ferries (Houchin and Green River) restrict to 16,000 lbs gross — most Class C rigs and travel trailers clear that, most Class A rigs do not.

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