The Gomantong Caves in Malaysian Borneo are not a place for the faint of heart.
There are two cave complexes; Simud Hitam or the Black Cave, which soars up to 90 metres high, and Simud Putih or the White Cave.
Those with a high threshold for claustrophobic and dark places infested with creepy crawlies can take a detour from a popular boat ride along the Kinabatangan River to the Black Cave's entrance.
As soon as you walk inside you are hit with how large and beautiful the cave system is, and how terrible it smells.
The source of the rancid odour is guano or bat poo, which has built up over the centuries and now stands in a huge pile on the cave floor.
The magnificent manure mound is the work of both the approximately two million bats that sleep there by day, and the thousands of swiftlets that roost at night.
Perhaps the most unpleasant feature of the cave is not, surprisingly, the huge amount of excrement in it, but what's scuttling along the floor.
The cave is crawling with cockroaches.
They crunch under the feet of anyone brave enough to enter, scuttle through the bat and bird waste, and occasionally fall from the tall walls onto the heads of visitors.
If you happen to have grown up in a 1970s London flat and are therefore weirdly comfortable with the presence of cockroaches, then the cave probably has something else to get your stomach churning.
Giant, long-legged centipedes move freely across the walls and floor, their huge bodies stretching the length of a man's hand.
Not only are their alien bodies enough to scurry into your dreams for months following your visit, they can pack a venomous and sickening bite.
They have to compete for floor space with fat, darkness dwelling rats, who fight for survival among a fearsome population of snakes.
Giant cave crickets and massive spiders also happily live side-by-side.
While the caves' adult population of bats have little to fear from their neighbours, their young often fall from their nests onto the floor below, only to be devoured by the cockroaches.
It is the unfortunate job of a small group of brave people to spend a large chunk of their lives in the cave.
The swiftlets beautifully crafted nests are considered such a delicacy that poachers will go to great lengths to steal them, including climbing up the caves' walls in the dark of the night.
To deter them and keep the birds' population booming, a 24 hour watch is kept, deep in the cave's bowels.
