Carlsbad Caverns.

Stalactites and stalagmites in Carlsbad Caverns in the Carlsbad Caverns National Park in the Guadalupe Mountains of southeastern New Mexico.

Large cave in Carlsbad Caverns with a lit path around the walls.

Coloured rock formations deep in Carlsbad Caverns in Carlsbad Caverns National Park, New Mexico.

Stalactites and stalagmites in Carlsbad Caverns in the Carlsbad Caverns National Park in the Guadalupe Mountains of southeastern New Mexico.

Stalactites and stalagmites in Carlsbad Caverns.

Coloured lights form eery patterns and shapes on Stalactites and stalagmites in Carlsbad Caverns.

Large stalagmite growing up towards the ceiling of a cave at Carlsbad Caverns in New Mexico.

Stalagmites grow up towards the stalactites growing down from the ceiling of a cave at Carlsbad Caverns in New Mexico.

Two large stalagmites growing up look like mountains in a Mars landscape.

Giant stalagmites growing up towards the ceiling look like prominent phallic symbols.

Stalactites and stalagmites in Carlsbad Caverns in the Carlsbad Caverns National Park in the Guadalupe Mountains of southeastern New Mexico.

A lit path winds through a large cave in Carlsbad Caverns.

Stalagmites, some forming large phallic symbols, while others forming shapes like trees, grow from the floor towards the ceiling of a cave at Carlsbad Caverns in New Mexico.

Ladder left behind by early explorers in Carlsbad Caverns in the Carlsbad Caverns National Park in New Mexico.

Stalactites and stalagmites in Carlsbad Caverns in the Carlsbad Caverns National Park in the Guadalupe Mountains of southeastern New Mexico.

Stalactites in Carlsbad Caverns in the Carlsbad Caverns National Park in the Guadalupe Mountains of southeastern New Mexico.

Stalactites and stalagmites in Carlsbad Caverns in the Carlsbad Caverns National Park.

Stalactites and stalagmites in Carlsbad Caverns.

A large erect phallic symbol or stalagmite, grows from the floor of Carlsbad Caverns in New Mexico.