Peak season Deer Cave Bat Emergence — Mulu Borneo
Deer Cave in Mulu National Park houses the world's largest population of free-tailed bats — an estimated 3 to 5 million Wrinkle-lipped free-tailed bats that emerge each evening in a continuous black column lasting up to two hours, forming one of the largest aggregations of mammals on Earth. The emergence is observed from an open-air bat observatory as the column writhes and spirals across the Borneo sky, morphing into shapes that hawks and bat hawks attack from above. Deer Cave itself is also one of the world's largest cave passages — 1.2 kilometres long and 174 metres high, containing a bat guano mountain 100 metres high and a section called the Garden of Eden where a roof collapse has created an interior jungle. The combination of geological grandeur and biological spectacle at this scale is genuinely without equal.
About this spectacle
Each evening at dusk, the mouth of Deer Cave releases one of nature's most astonishing sights: a continuous dark column of three to five million Wrinkle-lipped free-tailed bats spiralling into the Bornean sky. From the open-air bat observatory, visitors watch the living river of bats writhe and morph into ribbons, vortices, and sinuous waves as bat hawks dive through the column picking off individuals. The aerial ballet can last up to two hours. Before the emergence, visitors pass through the cave itself — a passage 1.2 kilometres long and 174 metres high, one of the largest in the world. Inside, the scale is cathedral-like: a guano mountain 100 metres high rises from the cave floor, and where the roof has collapsed, a lush interior jungle called the Garden of Eden grows in the shaft of light. The air is thick with the rustle and chittering of roosting bats. The combination of geological immensity and biological spectacle — millions of mammals streaming overhead against a jungle-edged sky — creates a sensory experience found nowhere else on Earth.
When to go
Jan — Dec
Getting there
Nearest airport: MZV. Nearest city: Miri.
Booking options
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