Hydrologic oddities: The foul creek from the Black Cave (Gomantong Caves, Malaysia)

Imagine that you are a psychologist designing an immersion exercise for someone with a set of phobias. Maybe the patient is afraid of nasty things, dark spaces, bugs, bats, and so on. It needs to be a dank, foul place, where the walls are alive; creepy-crawlies can drop off the ceiling anytime... Let’s run a small creek through it, just for good measure. 

Welcome to the Gomantong Caves in northeast Borneo! 

The view of cave entrance, looking out

When you hear about "Bird's nest soup", this is where the nests come from. Birds (swiftlets) make nests out of spit on the roof and the sides of the cave. People climb hours, 90 meters high with ropes and bamboo ladders (Health and Safety would seriously disapprove). This is the “Black Cave” (Simud Hitam) named because its nests are not as clean as the more valuable nests from the harder to access but larger "White Cave" (Simud Putih). 


Honestly, I have to wonder who was the first person to climb to the top of a cave to harvest a spit-nest and put it in soup. What are all the other things they experimented with along the way but gave up on? It's a bit like Fugu ovaries... They're the most poisonous part of a fish that can kill you on eating it. However, someone figured out that you can ferment the ovaries for 3 years and then there is a chance you might not die. 


Really, who is the unfortunate person who waited only 1 year to figure out that was not long enough? Worse yet, who were his friends who decided to wait longer and give it another go?  

On the way to the cave there is the typical wild-monkey-in-a-tree (Presbytis rubicunda)

So, in the cave are also bats... literally millions of bats. The birds and their bats do their business and poop on the floor. Untold centuries of poop forms the spongy bed of the creek that snakes its way through the cave. The smell is like a punch in the nose.

I tell you, it's really hard to photograph in a cave. Note, bat poo (foreground, background).

Excrement is full of nutrients and so you would imagine someone would be taking advantage of this incredible biological opportunity. Shine a light on the wall or the floor and you'll see...

... wriggling centipedes and an unfathomable mass of cockroaches. The boardwalk is steep and slippery so be sure to hold on to the handrail...

The handrail. Seriously. Grab on and potentially touch a roach or risk falling into a catastrophic failure. 

To give you a sense of how rank it is, the cave's creek (right) fouls the normal river (left) as they join.

The Gomantong Caves happen because limestone is easily dissolved by the water flowing through it. When a landscape has much limestone, it is called Karst. It's why some streams disappear in a hole only to pop out of a cave somewhere else.

Imagine how the center of a log rots out before the bark, leaving it with random little holes, tunnels, and other hollows. The cross section of, say, a live pine tree is pretty simple and easy to describe, but who knows what it looks like inside a rotten log. Similarly, "holey" limestone is one of the most difficult landscapes to model in hydrology. On our search for "hydrologic monsters", we'll likely spend a lot of time near Karst.

By the way, the birds nests are so valuable that the cave is heavily guarded by the government. In the back of the cave there is a place for the guards to sleep. It's a terrible job, poisonous snakes and centipedes have been known to bite them and cockroaches eat at their skin when they sleep. At least there's a cave cat (the glowing eyes in the center right of the below picture) that keeps them company (while feasting on birds). 

I think this counts as a zero-star accommodations