'Ohmygod, ohmygod, ohmygod, DARK WATER! ohmygod, ohmygod, ohmygod, NOOO!' is how it normally goes when I'm faced with my nemesis. I've long had a phobia about murky depths, and a phobia it most definitely is, because it even affects me in the bath. I kid you not; if I'm in the bath and someone turns the light out, I completely freak – that's a phobia, no doubt about it. Peta once brought along a selection of scented candles on a skiing holiday so we could have some nice, romantic candlelit baths after a hard day on the slopes. It didn't end well; I don't tend to relax when screaming.
So the thought of coming back from Mérida to Playa del Carmen to go scuba diving in a cenote wasn't exactly top of my list, but cenote diving is one of the unique experiences of this part of Mexico, and it would be silly not to at least try it. A cenote (pronounced 'seh-no-tay', from the Mayan for 'water-filled cavern') is a flooded limestone sinkhole that's formed when the roof collapses on an underground river. Being made of limestone, this part of the Yucatán is riddled with underground lakes and rivers formed by rainwater seeping through the ground, and this porous geology has created a collection of some 6000 cenotes, surrounded by forest and connected to each other by endless miles of flooded caves and river systems, most of which is still unexplored.
The most accessible cenotes aren't quite so mysterious, and every dive operator in the area promotes cenote diving alongside the more traditional reef dives off the island of Cozumel, so when we turned up in Playa, fresh from the five-hour bus ride from Mérida, and found we couldn't get space on a Cozumel dive for a couple of days, we figured we'd try a cenote dive in the meantime. So we signed up with Dive Mex, the people who'd taught Peta to dive, and rolled up the next day to meet our guide, Dario, and another paying customer, an affable American from Oregon called Roger, who'd been diving since the 1970s.
Dive One: Kukulkan
Now, bear two things in mind. First, this was Peta's first real dive following her course; sure, as part of the PADI Open Water course you have to do four dives in open water (in her case, the sea), but these are part of the course rather than independent dives, so this was Peta's very first dive as a qualified scuba diver. And second, I'm deeply phobic about dark water, I get claustrophobia, and I hate large cavernous spaces, like aircraft hangers. It turns out that cenote diving needs you to be in control of your buoyancy – one of those skills in scuba that takes time to learn, much like stability on a bike – and it also consists of a lot of enclosed, dark water and, um, cavernous spaces. As a team, we couldn't have been less suited to cenote diving.
The first dive didn't go well, it must be said. Dario, a middle-aged Italian man who thought (and probably wished) he was a lot younger and more handsome than he actually was, drove us out to the Chac Mool cenote, on the way south to Tulum. Here, in the shade of the forest, he talked us through the two dives we'd do and showed us the dark and menacing-looking cenote entrances – one called Kukulkan and the other called the Little Brother – before taking off his groovy yellow aviator sunglasses, stripping to the waist, sucking in his chest like Val Kilmer in that famously homoerotic locker room scene in Top Gun, pulling on his wetsuit, and jumping into the cenote entrance, which at this point was little more than a rock pool. We struggled into our suits in the heat and waddled down to the entrance with our tanks on our backs, and there was Dario, trying to rush us into the pool. 'Come on, jump in,' he shouted, while we flapped about on the side, trying to make sure we hadn't forgotten anything vital.
Cenotes in Mexico can be busy places with lots of divers, so there's an element of crowding that the guides obviously want to avoid, but rushing a total novice and a diver with a phobia is going to end badly. When we were doing our buoyancy checks to ensure we had the right amount of weight strapped to our waists – you let the air out of your jacket and sink into the water, breathing normally, and when you have the correct weight your eyes should be level with the water – I had a panic attack at the dark water beneath me, and had to tell Dario to go and check someone else first, while I calmed down. He looked at me in the way that Italian men do when they encounter a member of the male sex who might be showing feelings – it isn't an enjoyable look to be on the other end of – and went to help Peta while I spluttered around and tried to calm myself down.
'It's OK,' I thought. 'We're only qualified as open water divers, so we'll always have open water above our heads, so if it gets too scary, we can just go straight up. It'll be fine.'
And so once Peta's weights were sorted out, and I'd calmed down enough to breath underwater – well, to gulp air in short, panicky bursts, if I'm going to be honest – we set off on our first cenote dive.
If you look at the PADI website, then it talks a bit about cavern diving. Flooded caves have two zones: the cavern zone is the area where you can still see the cave entrance, and you're no more than 40m down (the limit for decompression diving); if you get into trouble, you can cover your torch and can see where to swim to. The cave zone, meanwhile, is cut off from the outside world, and you can't see daylight, so you need proper equipment and training to go this far. If you're a cavern diver and you veer into the cave area, you risk your life; just to clarify our minds, it turns out that two Brazilian honeymooners and their guide died in Chac Mool in April 2012 when they went past the safe limit (through they were the first divers to die from human error in this area since the early 1990s, so it is a pretty safe thing to do).
If you want to go diving in caverns, then PADI has a course for that (they have a course for everything, being a money-making machine). Once you've got your Open Water, you can move on up through Adventure Diver and into Advanced Open Water Diver, and then you can take the speciality Cavern Diver course, to teach you all about diving in caverns. By this point you'll have learned how to control your buoyancy so you can make the fine movements up and down that you need when negotiating underwater caves; you'll also have learned about the special safety procedures you need, how to navigate through cave systems, how to use underwater torches and reels, and so on. It's pretty involved.
They don't teach you any of these things in the Open Water course, but that doesn't seem to bother the Mexican diving community, because Dario seemed perfectly happy to take a total novice and a phobic into Chac Mool without so much as a pause for breath. It was only when Peta's buoyancy spun totally out of control that he started to wonder whether this was a good idea, and like all strutting Italian men, he started to get impatiently annoyed, which only made things worse. He tried to signal to Peta what she should do to correct her spinning, but following his instructions only seemed to make things worse, and after ten minutes or so we surfaced. Here he decided that criticism would be a more effective way of helping Peta out, rather than gentle kindness, so Peta and I swam out of the cenote and stomped back up to the truck, while Dario took Roger off to see the depths of the cenote.
It turned out that Peta had kept rolling over onto her sides, which tends to be a sign that the weights aren't equally distributed around the belt; Dario had been telling her to fix this by inflating her jacket, which only made things worse, so while Dario and Roger explored Kukulkan, we had a bit of a team talk.
'I really don't like that Dario guy,' confided Peta. 'He's just not a very nice person.'
'Ignore him, then,' I said. 'We'll get the weights right, and you just concentrate on getting your buoyancy right.'
'Well, at least you did OK,' she said, and that's when I realised I'd been so distracted by Peta's problems, that I'd practically forgotten we were in a cave. In dark water. In an enclosed space. With lots of rock above us and, at times, hardly any daylight at all. The thought made me shudder.
Happily, when Roger and Dario came back for lunch, Roger – who was a very experienced diver and specialised in consuming minute amounts of air by staying amazingly calm and being really efficient with his movements – was kindness personified and talked Peta through how she could make her buoyancy work better. 'Oh, and I don't think he's right,' he said when Dario had gone to get our sandwiches for lunch. 'I don't think your problem is bad buoyancy control; I think your weights are off-balance.'
So when we went back for dive two, we made sure the weights were properly distributed, and hey, guess what? We dived like experts who'd been doing it for years. Well, we did compared to the first dive, anyway...
Dive Two: The Little Brother
So, what's it like, diving in a cenote? Well, if you have a phobia of dark water and enclosed spaces, then this is about as close to hell as you can get. Now that I wasn't distracted by other things, my entire second dive was little more than a controlled underwater panic attack, but once I realised that I wasn't imminently going to die, I applied the same state of mind that I had when walking through utterly petrifying Tunnel Creek in northern Australia, or my first night dive on the Great Barrier Reef. I just stopped thinking about it and crushed any thoughts that might set me off.
For cenote diving is cave diving, for all intents and purposes, and my initial thoughts of always having open water above me were way off the mark. Dario gave each of us a torch, because at times you are swimming through pitch black caverns of deep, dark water, and you have no idea where the outside world is. Most of the dive through the Little Brother cenote was like this, and above our heads was the cavern roof – no air, just the roof – so when I did screw things up and pressed the wrong button, I'd shoot up and crash my head on solid rock. You learn to watch your control in places like this, especially when you spill out into a wonderland of stalactites and stalagmites that you have to thread through gently, trying not to get snagged on anything. At times it's like flying, because the water is so clear that it's easy to pretend that there's nothing but air beneath you (though as soon as I thought that, I suppressed it immediately; that way vertigo lies).
It didn't help that Dario had given me the only torch that kept conking out. In fact, this was my second torch; the first one he'd given me had a broken strap, so it almost immediately fell off my wrist and I had to dive down and pick it out of the rocks near the entrance. The second torch died in one of the blackest parts of the cave, so there I was, trying not to panic as I smacked the torch back into a dim flicker, while Dario and Peta, who were ahead of me, slipped into the distance in their own personal bubble of light. Luckily Dario had a third torch, which he gave me later on when he saw me struggling, but that one had such a crappy beam that it was almost not worth bothering.
This became apparent when we surfaced in an air dome at the top of the cavern, where there's about a metre or two of air between the dark water and the cavern roof. Lit only by divers' torches, this is an eerie place where tree roots dangle down from the rock into the water, and spiders crawl on the roof among strange hair-like webs. The air is breathable because there's a hole that connects it to the outside world, but it doesn't feel connected to anything; it feels like the bowels of hell.
Oh, and just in case you thought that a functioning torch is all you need to find your way through a cenote, it isn't. There are areas throughout the cavern where lighter fresh water sits above heavier sea water, and where the two types of water met, you get what's called a halocline, and visibility reduces instantly from perfectly clear to mere centimetres. The effect is a little like looking down a kaleidoscope, or if you're a migraine sufferer, it's like the kind of visual effect you get when a migraine is kicking in, except covering your whole field of vision. It's freaky to see the divers just in front of you disappear in a cloud of psychedelia, as if swimming through a pitch black cavern weren't trippy enough.
But we made it back, having managed to follow the entire prescribed route through the Little Brother cenote, and it was only when we blinked our way out of the water and into the sunlight that I could look at Peta and finally admit that yes, I was underwater, in the dark, in a cave, and just about holding it together.
So I'm glad we dived a cenote, but like sailing the Pacific, once was enough for me. I'd much rather dive over picturesque reefs with the sun beaming down through the azure sea, where there's life and the big, blue sky above me. There's no life in the cenotes, apart from a few tiny fish at the entrance, and it's easy to see why the Mayans thought the cenotes were the entrances to the underworld. Deep down, it is the underworld, and frankly, I'm much happier up here in the light.