Visit the Moqua Caves

Drop into a limestone sinkhole of crystal-clear fresh water on the Yucatan, where the Maya saw the entrance to the underworld.

Limestone cave with a swimmable freshwater pool on Tongatapu.

Nauru’s best beach, a curve of sand and coral pinnacles on the east coast, with a harbour and swimming lagoon.

Jagged coral pinnacles of the interior.

Turquoise limestone pools stepping down a jungle river that vanishes underground beneath them.

Hike a palm-lined canyon to turquoise pools, then swim through a crack in the rock into a hidden cave waterfall.

Explore the stunning underground landscapes of Carlsbad Caverns in New Mexico, USA

Explore the unique underground labyrinth of Wind Cave National Park, known for its boxwork formations and one of the longest caves in the world