Really, how could I resist? The chance to explore a remote flooded cave system, stuffed with ancient Mayan artefacts and the skeletons of sacrificed women and children, deep in the rainforest... isn't that what everyone dreams of? Of being Indiana Jones for day?
Frankly, no, it isn't. I hate caves, I get claustrophobia, I don't like dark water, and I can live without bats flying round my head and cold water dripping onto my face from ancient stalactites, however pretty they are. I have nightmares about caves; Indiana Jones, I am not (although I do have the hat).
But, as with the Blue Hole, it seemed churlish to come all this way without visiting Actun Tunichil Muknal cave, especially as none other than National Geographic in its book 'Sacred Places of a Lifetime' rates it at number one in its list of Top Ten Sacred Caves. And hey, if I can scuba dive in a completely flooded cave and survive, surely I could try a bit of spelunking and survive. I mean, it's only claustrophobia...
Into the Forest
You have to take a tour if you want to visit Actun Tunichil Muknal (which is Mayan for 'Cave of the Crystal Sepulchre'). This is not only because it's a delicate archaeological site that would be trampled into oblivion by unfettered tourism, but also because it's a hell of a trek to get to the archaeology in the first place. When you sign up for a tour there are some simple rules: first, no cameras are allowed anywhere in the nature reserve that contains the cave, ever since a tourist dropped his camera on a 1000-year-old skull and smashed a hole in it; second, you need to bring a set of clothes that you don't mind getting completely wet (though not beach gear, as that wouldn't be respectful enough for this sacred site); and third, you need to bring a pair of socks, so you can walk around the archaeology without stomping it into pieces with your shoes, or leaving oils from your feet that will mess with the natural flow of water over the delicate surfaces.
These rules tend to put off your typical ten-sites-in-a-day, air-conditioned coach tourists, putting this attraction in the 'adventurous' category. And adventurous it is, too. After an hour's drive from San Ignacio, half of which is along incredibly juddering dirt roads, you reach the entrance to Tapir Mountain Nature Reserve, where the park warden sticks his head in the van and tells you not to touch anything, not to use cameras, and to listen to everything that the guide says you must do. And he smiles a happy smile, wishes you a good day, and off you go into the small car park next to the park office.
This is where the fun starts. Grabbing nothing except a caving helmet with attached head torch and a bottle of water, you slip into your set of wet clothes and set off through the jungle on a 45-minute trek (though not after your guide has warned you to keep an eye out for snakes). The first river that you have to wade across, Roaring Creek, is cold and waist deep, and at maybe 20m across it's a bit of a shock to the system at 8.30am. The second river – Roaring Creek again – is even faster-flowing and even colder, though by the third one – yes, you guessed it, it's Roaring Creek for a third time – things are still a bit numb, so it isn't quite as uncomfortable. At the small shelter near the entrance to the cave you leave your water bottle stashed away in the eaves, and then it's off to the hourglass-shaped cave entrance, which is dark, flooded and distinctly uninviting when you're already shivering from the river crossings. The ancient Mayans believed that Actun Tunichil Muknal was the entrance to the underworld, and the the locals still call it Xibalba (pronounced 'Shi-bal-ba'), after the name for the Mayan underworld. It's not hard to see why.
Our guide, Orlando, was a charming Mayan with kind eyes and a patient soul, and it was his smile that got me swimming across the first pool of dark water and onto a rock where we all crouched down, peering nervously into the shadows beyond. From that point on it was single file, passing messages down the line like 'watch your knees on that rock there' or 'don't smack your head on this'. We walked through a fast-flowing river, heading upstream through small tunnels and into large chambers with bats flying around our heads, before ducking under stalactites and rock flows that glittered in our torch light; and all the time we walked through waist-deep water, trying to feel our way through the rocky riverbed without twisting an ankle or bashing a knee on anything sharp.
Every few minutes, Orlando would wait for the group to bunch up and would show us something interesting; he pointed out sparkling rock formations, he showed us black deposits of manganese and white deposites of calcium, and he even demonstrated how one of the rock flows looked like a wedding dress seen from behind on a particularly shapely bride. And then he got us all to stand waist-deep in the flowing river before making us turn off all our torches. Yes, absolutely every one of them; it suddenly became completely pitch black, deep inside a cave in the bowels of the earth, while he told us we were in the Stelae Chamber, and how the Mayans had carved two of the rocks here into special shapes. One was in the shape of the obsidian blade that they used for bloodletting, and the other in the shape of a maize cob, or if you're feeling fanciful, a sting ray's spine, which they also used for bloodletting; apparently the Mayans would use blades and spines to cut the tongue, or the foreskin of the penis, or even cutting off a finger tip, and they'd offer the resulting blood to the gods.
And then Orlando turned on his torch and shone it on a rock that, yes, did indeed look like a sting ray's spine, and the shadows it cast on the dark water and cavern walls danced all around me, pointing at me and saying, 'Ha! Dark water! You're standing in dark water! It looks just like blood!' I suddenly felt as if my spine was indeed made of sting ray, and I had to think happy thoughts until he let us all turn our lights back on and we headed further into the cave, distracting me from my first panic attack of the trip.
There were some tight squeezes, too, where we had to turn our bodies side on, sink chin-deep into the water one at a time, and twist through the small tunnels to get through to the other side, with water churning around our necks. When you're in a line, there's not much you can do except swallow hard and go for it; this is how you conquer phobias, by confronting them, and that's exactly what I had to do. I thought of nothing and didn't dwell on thoughts of miles of rock above my head, or the closeness of one's breath when you're passing through a tiny gap that you have to turn to pass through, or the possibility of jamming one's helmet into the tiny gap above the water line that's surely smaller than your head, getting stuck and never being able to move again... but eventually we reached the half-mile point where the rest of the three-mile river system disappears off into the mountains. There are no more archaeological artefacts upstream from here, and instead the good stuff is in the prehistoric chambers above the river. And so the climbing begins.
There are no guide ropes, no ladders, no man-made hand-holds or steps in Actun Tunichil Muknal; there's nothing modern at all save for some red tape on the ground that shows where the artefacts are, so climbing the almost vertical wall of slippery rock into the upper caves is no mean feat. You're wet, you're slippery, you're cold and you're tired, but you have to put your right foot here, your left hand there, swing your left foot round here, twist your body through 90 degrees, and pull yourself up with your hands to get onto the small ledge at the top. It's amazing that more people don't slip and injure themselves seriously; one rather suspects that it's only a matter of time before the cave claims its first modern victims, but for now it's all about the ancient victims in the caves above, and they're definitely worth the risk.
At the top of the climb you have to take off your shoes and put on your socks, and from this point on the air is still and smells dank and musty, a heady mix when you combine it with the overpowering smell of tourist's armpit. It's the same claustrophobia you get on a packed day on the London Underground as your guide points out the first artefacts, broken pots that are half buried in the cave's sandy floor, left untouched since the Mayans smashed them on the ground sometime towards the end of the classical period, between 700 and 900 AD. He also casually mentions that this is the spot where a fellow guide was trapped for ten hours when a flash flood hit the river below and it rose to block the exit. 'Oh, and he had guests with him,' he adds with a wink, and suddenly it's all a bit too real.
And then it's a squeeze through a small opening in the rock, before wham! The cave opens up into a huge cavern, littered with broken pottery and old fireplaces, while large flowstone formations crown the roof high above your head. There's a sequence of five chambers, each more impressive then the one before, and it isn't long before you're staring at your first skeleton, with the skull sticking out of the cave floor, the femurs to one side, and the rib cage visible in a jumble of backbone. The upper caves used to flood and the water moved the bones from their original resting place, where the Mayans sacrificed their offering to the rain god, Chac, smashing the poor soul on the side of the head before ripping open the rib cage, pulling out the heart and sticking it on the fire. They believed that the smoke from the burning heart would please the rain god and the droughts that eventually brought about the fall of the Mayan civilisation would recede, but all that's left are the bones of the sacrificed and the stories of the guides, told deep underground just inches away from the sacrificial skeletons.
There are 14 skeletons in all in the cave, ranging from a one-year-old to adults (though you only get to see a handful of them). Some of the skulls have flattened foreheads, which the Mayans used to think was beautiful; they would bind a plank of wood to a child's head and leave it there until the forehead was flattened, and they would also force the child to look at its nose for weeks on end, eventually making the child cross-eyed. Finally, they would stick jade teeth into their mouths, leading to a flat-headed, cross-eyed, jade-mouthed look that doesn't sound as appealing to modern ears as it presumably did to the ancient Mayans. One poor child even had his arms bound before being killed; he's the one with a tourist-inflicted hole in his head, which only adds insult to injury.
But the queen of all the skeletons is the Crystal Maiden, a 20-year-old woman who lies on her back at the end of the cave system. She's been there so long that her bones have calcified, giving her a crystalline and slightly puffed-up appearance; it's hard to tell where the cave floor ends and she begins, as she glares at you from her 1000-year resting place. This, you remember, is the Mayan underworld, and staring into the sockets of the Crystal Maiden, it's hard to suppress the subterranean shiver that shoots down your sting-ray spine.
Into the Light
Of course, you now have to go back out the way you came in, and climbing down the slippery rocks is even harder than climbing up. Luckily you're going with the river flow this time, so the river sections aren't so bad, and it isn't long before the daylight blinks in your eyes and you have to swim back across to the cave entrance. Oh, and you then have to do the 45-minute trek again, wading across Roaring Creek three more times before collapsing into a juddering bus that shakes all the cave water out of your ears before dumping you back in San Ignacio for a well-earned bottle of stout.
It's a proper caving adventure and isn't for the faint-hearted, but it's worth it to stare into the depths of the Mayan underworld. If that doesn't make you appreciate the sunshine, I don't know what will.