This survey, made by the Hoffman Institute at Western Kentucky University, revealed the maximum cross-sectional area to be in the large southern passage.

The movement of the Asian and Australian tectonic plates caused the crust to buckle and elevate the land once more, giving birth to the island of Borneo and the Mulu mountains, around five million years ago.

To access Deer Cave, one must first enter the Gunung Mulu National Park, by way of Kota Kinabalu or the nearby city of Miri.

This walk is considered an additional attraction to visitors as it takes them through the rainforest (of about 55,000 ha (140,000 acres))[7] and by an ancient Penan Burial Cave.

[citation needed] To the northeast the cave opens into the so-called Garden of Eden, an approximately 1 km (0.62 mi) wide, circular depression encircled with 150–300 m (490–980 ft) tall limestone walls from three sides and a mountain slope from the fourth.

The Garden of Eden is a karst valley or sinkhole with a volume of 150 million cubic meters, its bottom is covered with rainforest.

[8] In 2008, Prince Albert II of Monaco visited the Gunung Mulu National Park to launch a new camera system as part of the Bat Observatory, which is located near the entrance of the Deer Cave.

It is part of the Gunung Mulu National Park, a UNESCO World Heritage Site characterised by amazing caves and karst formations in a mountainous equatorial rainforest setting.