The Mulu Caves are located in the Gunung Mulu National Park in Malaysian Borneo. The park encompasses incredible caves and karst formations in a mountainous equatorial rainforest setting. The Sarawak chamber found in one of the underground caves is the largest cave chamber in the world. It has been said that the chamber is so big that it could accommodate about 40 Boeing 747s, without overlapping their wings. The enormous colony of Wrinkle-lipped bats in the nearby Deer Cave exit almost every evening in search of food in a spectacular exodus.