The mouth of Deer Cave in Gunung Mulu National Park (Borneo)
This is the cave mouth on the side of the "Garden of Eden", i.e. the far side.
Deer Cave is a passage about 150 m (500 feet) in diameter and about 1 Km (0.6 Miles) long, opened on both end. It was, for many years, considered the largest single cave passage in the world.
Photo processed in True Tone HDR with Tone Mapping from a single RAW exposure.