Big holes, tunnels and cave systems with the biggest known cave chamber (Sarawak Chamber) exist here in Mulu National Park. Some of the caves are show caves with boardwalks and artificial lights on the stalagmites and stalactites, but real caving trips are also possible to arrange with one of the national park's experienced guides. Seeing the Sarawak Chamber (600 m x 415 m x 80 m) is a very difficult and demanding expedition, so don't count on seeing it on your first trip underground. Overground, the jungle and its wildlife can be explored from canopy walks spanning between the tree tops. Don't forget to see the bat exodus at dusk, where millions of bats set out from the caves on their hunt for food. They just keep coming out and draw thick waves in the evening sky. An incredible sight not to be missed.