The Deer Cave, which contains the world's largest cave passage,is the nearest show cave to the park headquarters. A three-kilometreplankwalk passes through a peat swamp, alluvial flats and limestoneoutcrops before reaching the cave entrance. It is worth takingsome time to reach the cave as there is much to see along theway, including an ancient Penan burial cave and fine examplesof the ipoh tree, the rainforest giant from which the Penanextract poisonous sap for use in their blowpipe darts.
Upon reaching the cave entrance, the visitor quickly realisesthat the statistics must be true; the cave is simply huge. Itis just over 2 km in length and never less than 90 metres highand wide. The main chamber (174 m wide and 122 m high) is partiallylit by sunlight. It is here that Sambur deer used to shelter.The local Berawan and Penan people, who have known the cave forcenturies, have always referred to it as Gua Payau or GuaRusa (Deer Cave).
An illuminated path leads around the cave, but a flashlight isuseful for examining the insects that dwell on the guano-coveredcave floor. After about an hour of steady walking, the path passesunder a hole in the cave roof and the so-called "Garden ofEden". The rich greens of the vegetation that thrives inthe shaft of light contrast sharply with the rest of the cave.
Deer Cave is also home to a number of species of bat. At dusk,if the weather is fine, visitors are treated to the spectacularsight of thousands of bats emerging from the entrance of the caveto go in search of food. This swarming cloud of bats is set againstthe changing backdrop of the early evening sky. A specially builtbat observatory provides a pleasant resting area, giving visitorsthe opportunity to take it easy with a cold drink until the "show"begins.
After a tour of Deer Cave the park guides usually take visitorsto Lang's Cave, whose entrance is a short walk from that of DeerCave. Although Lang's Cave is the smallest of the show caves,its rock formations are perhaps the most impressive. Strategicallypositioned lights highlight the most interesting formations.