World’s biggest cave – Sarawak Chamber, Malaysia

If size of cave was a status symbol, then only a Stone Age King would be able to claim the Sarawak Chamber in Malaysia.
Discovered only in 1981, this huge cavern on the island of Borneo is the biggest in the world, and is part of an extensive cave system.
To get some idea of scale, it takes an hour for even experienced cavers to get from end to end, and headlamps usually aren’t strong enough for them to see the walls.
In terms of what could fit in it, then think St Peter’s Basilica in Rome or a decent collection of jumbo jets.
To get there, you’ve got to make your way through a few tricky passageways, so the guides at Gunung Mulu National Park insist that anyone they take must have previous experience.
However, they do allow you to get that by doing a trip to other caves in the recently-declared World Heritage Area.