Visit the Phong Nha caves

Paddle 8 km into a limestone cave where a river flows straight out to the sea — one of the New Seven Wonders of Nature.

Gunung Mulu’s vast cave system, including the Deer Cave and its nightly bat exodus.

Drift between the American and Eurasian tectonic plates in gin-clear glacial water.

Row through limestone karsts and rice paddies on the "Ha Long Bay on land", then climb to the Mua Cave viewpoint.

Sea cave on the Algarve coast with a round skylight in its domed roof — reached by boat, kayak or paddleboard.

Karst islets, mangrove channels and Taino cave art.

Sheer fiord of waterfalls and peaks.

Walking safaris on the Zambezi floodplain among famously relaxed elephants.