See The Bats Of Deer Cave

The adventure

Deer Cave is enormous. Its main passage is so vast that daylight floods in from the entrance and a stream runs along the floor, and it is home to a colony of wrinkle-lipped free-tailed bats estimated in the millions. The air smells of guano, and swiftlets and bats flit through the gloom high above.

The show happens in the late afternoon. From the bat observatory near the entrance you watch the first few leave, and then they pour out in long, twisting columns that snake across the sky, sometimes for half an hour or more. Bat hawks swoop in to pick them off, and the columns ripple and change shape to dodge them. All of this happens in a national park of limestone pinnacles and dense rainforest, and the evening walk back through the jungle is filled with the sound of insects.

Why it’s epic

Gunung Mulu National Park became a UNESCO World Heritage Site in 2000.
Deer Cave was long thought to have the world's largest cave passage, until Son Doong in Vietnam was surveyed.
The nearby Sarawak Chamber is one of the largest known underground chambers in the world.
The Pinnacles, razor-sharp limestone spires up to 45 metres tall, are reached on a tough three-day trek.

What it is

Deer Cave has one of the world's largest cave passages, and millions of bats stream out at dusk.

How to do it

Fly to Mulu from Miri or Kuching and join the guided walk to the bat observatory at dusk.

Top tip

Stay a few days to explore the other show caves and the canopy walk.

Need to know

Mulu has no road link to the coast, so most visitors fly in on small planes from Miri or Kuching.
The bats emerge most reliably on dry evenings, and heavy rain can cancel the show.
Book park accommodation and guided cave tours ahead, as numbers are limited.

Plan this trip

Rough cost: £2,000 to £5,000 per person, including flights from the UK
Time needed: 1 evening
Best time to go: All year (dry evenings are best)
Fly into: MZV airport

Long-haul flights to Borneo and the extra hop to Mulu are the main costs; the park itself is good value.

Make it happen

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Why it’s on my list

Mulu Park – Malaysian Borneo

Not surprisingly, Deer Cave is home to many species of bats. Between 5 and 7pm, if the weather is fine, visitors may be treated to the spectacular sight of a black cloud of free-tailed bats emerging from the entrance of the cave to go in search of food.

Originally, this cloud was thought to contain hundreds of thousands of bats but a recent study that the figure is well over a million.