The Deer Cave is named after the deer which frequented the cave and which native hunters pursued. It is large enough to hold London's St. Paul's Cathedral five times over and is believed to be the largest cave passage known to man.

There are two entrances at either side of the cave. Thousands of bats live in this cave, and the odour from their droppings (guano) is noticeable some distance away from the mouth of the cave. Other cave dwellers include swiftlets, earwigs, centipedes, spiders, crickets, scorpions and white crabs.

The silhouettes of some of the cave’s limestone formations have been creatively interpreted; notably the profile of Abraham Lincoln. Adam’s and Eve’s Showers, at the East End of the cave, are hollow stalactites; water pressure increases when it rains. This darker section at the East End of the Deer Cave is the preferred habitat of the naked bat. Albino earwigs live on the bats’ oily skin and regularly drop off.

The cave’s east entrance opens onto ‘The Garden of Eden’ – a luxuriant patch of jungle, which was once part of the cave system until the roof collapsed. The West End of the cave is home to several million wrinkle-lipped and horseshoes bats. Hundreds and thousands of these bats pour out of the cave at dusk. Bat hawks can often be seen swooping in for spectacular kills.  

A three-kilometre long walkway links the Deer Cave with the Park Headquarters. The walkway passes through virgin tropical forest where one can observe a huge variety of plants, orchids, insects, and other animals.