Carlsbad Caverns National Park

The Big Room is the draw: a self-guided trail of about a mile around a single vast chamber crowded with stalagmites, columns and draperies. It is the most flexible big-cave visit on this list, because you can walk down through the Natural Entrance on a steep switchback trail or ride an elevator to the Underground Rest Area, 750 feet down, and start from there. The Big Room Trail is the only wheelchair-accessible route in the cavern. The Natural Entrance trail, at a 15 to 20 percent grade, is hard on the knees, so walking in and riding the elevator out is the kindest way to see both. Reservations for an entry time are strongly recommended. Time the day to finish with the ranger-led bat flight program, when thousands of bats leave the cave.