WHEN YOU SURFACE with just enough gas to fill your BC you know you’ve had a great dive or a bad one. Thankfully, for me, it was the former.
I’d just dived Tortugas Reef off Playa Del Carmen on Mexico’s Cancun coast and I won’t forget it in a hurry. I say that not to brag about my poor air consumption or devil-may-care attitude to personal safety, but to try to convey the sheer excitement of the dive.
My guide and I had dropped off the boat into a two-knot current and descended to the seabed at 16m. It was a pretty boring-looking reef, just a flat of sponges, brain corals and algae, but almost immediately the reason for our visit came swimming into view. Tortugas is Spanish for turtles, and this reef is home to the hawksbill variety, and a lot of them.
Hawksbills are critically endangered, but because they eat stuff divers like to look at we see them often. Generally we see one or perhaps two on a dive – but rarely 10, as here.
The first one swam slowly, but in the current it zipped by in a moment. I spotted another grazing to my left. I kicked against the current and, as I reached it, I spun and finned hard to keep still beside the marine reptile. It was hard work, and with pictures taken I spun around again and resumed my flight.
A minute went by until my guide indicated another turtle off to the right. I finned that way and performed the same spin, fin hard and pivot back on track.
Then another appeared, then another, and another. Within minutes we’d seen half a dozen turtles and my breathing was thumping. My heart threatened to jump from my chest and slap me around the face. I was exhausted.
As the depth nudged 20m, I glanced at my nitrox pressure and saw that it was below 100 bar. I haven’t breathed that fast since my open-water course.
Another turtle came into view, and I was down to 70 bar by the time I’d finished. My body clamoured for oxygen to feed my overworked muscles.
My guide had not finned against the current, so had plenty of nitrox left, but I had just enough dregs in the cylinder when I reached the surface, shattered but ecstatic. It was the type of challenging dive I love.
I had come to Mexico’s Caribbean coast during bull-shark season. Unfortunately no one had told the sharks and they’d left the week before, but that’s nature for you.
Not that it mattered, as there is plenty of excitement without them.

PLAYA DEL CARMEN lies on the Yucatan Peninsula opposite the island of Cozumel. I travelled with tour operator The Scuba Place, stayed at the Allegro Playacar resort and dived with Pro Dive Mexico, which has dive-centres all over the area and enough scuba programmes to keep anyone entertained.
The next reef, though less well-endowed with turtles (only two) was slathered in fish. Shoals of French grunt, white grunt and Atlantic spadefish put on a show of force. Some hung out on top of the reef plateau, but the grunt and snapper preferred to shelter beneath the overhanging ledges.
Barracuda, as the reef is known, is named because you encounter the beefy-looking fish here. Throughout the dive several large individuals hove into view like a pack of wolves following an injured deer. But they never got too close, just saw what we were and left.
Tortugas and Barracuda were heart-thumping dives with adventurous overtones, but even they paled when compared to my next dive.
I have dived caverns before, even popped into a mini sea-cave, but I have never before driven into a jungle and jumped into a hole in the ground.
This area of Mexico is famous for freshwater sinkholes called cenotes. The entire Yucatan Peninsula was, at one point, a vast coral reef in a tropical sea. Millions of years of coral growth laid down a limestone plateau, but 66 million years ago a meteor hit the area, creating
a crater 112 miles in diameter and 12 miles deep.
Known as the Chixulub Crater, the forces that created it triggered a massive change in the Earth’s geology and biology.
The meteor strike was the pivotal moment that caused the dinosaurs to die out. The impact threw the Yucatan up out of the water and cracked the limestone strata, allowing water to flow within the shelf.
When water and carbon dioxide mix, they form carbonic acid. Acid dissolves limestone (calcium carbonate) and the fractures within the shelf developed into a series of fissures and caves.
In the intervening millions of years meteor strikes, pole shifts and tectonic movement have caused the water to rise and fall across the Yucatan, exposing the caves to dry and wet periods.
When dry, dissolved calcium and other minerals formed stalactites as water dripped from the roof of the caverns. Below them, growing at about a third slower, stalagmites formed.
When the sea level rose these formations froze in time, only to resume their geological desire to reach each other when the water-table dropped.
When the last Ice Age abated, rising sea-levels pushed the water table up and into the caves. Erosion also took its toll, and while most of the cave systems run below ground, in places the limestone has collapsed, exposing sinkholes.
These are cenotes, and some 2200 have been discovered to date.
Many are open to cave-divers, and a few are safe enough for recreational divers if accompanied by a qualified guide.

DIVING A CENOTE is like nothing you will have done before. It is a combination of excitement, fascination and a dramatic light show (when the sun shines).
You can book a cenote diving package from any Pro Dive Mex centre and are bussed to its cenote centre where you are met by your guide, kitted out and taken for an adventure. Tavo was my cave dive-guide, and my first cenote was Chac Mool.
Most cenote lie on private land, and to allow divers into them the land-owner must provide some basic amenities such as a road and parking area plus a toilet.
The ones I visited also had a changing area, and Chac Mool even has a cafe. It sounds touristy, but is pretty rustic.
The jungle is dense, but the trees are small because of the limestone crust and high water-table. As the roots reach downward, they encounter water too close to the surface to allow further growth.
Chac Mool has two entrances. The first is an open pond below which the cavern opens. As the daylight behind faded and the way was lit only by my torch, an eerie light ahead started to brighten the cavern.
This is where the light show kicks off in the morning, when the sun lances through the foliage of a mangrove stand. It’s possible to surface here, and although I was only a short distance from the car park it felt like the middle of nowhere.
Exotic bird-calls punctuated the forest silence. It’s a surreal experience to swim through a flooded cavern and out into an ancient world. I almost expected to see South American tribesmen peering around the trees at the two explorers who had just emerged from their sacred water hole.
But, of course, that was fantasy. What looked like a fantasy, but wasn’t, was the display mounted by the emerging sun.
The light, ripped apart by the leaves above, lanced down into the crystal fresh water, creating a stunning visual spectacle.
I was captivated and wanted to see more, but the weather closed in and clouded over. So we stopped for lunch and a change of tanks before entering the second chamber.
This had a smaller entrance and created a real sense of adventure. To reach the sun side we dropped below the surface and swam past stalactites and stalagmites and over boulders and limestone slabs.
Then the darkness ahead lightened. Another open area came into view, and Tavo and I again surfaced into the jungle.

IT WAS AS SERENE as the first time, but the clouded sky above showed no promise of clearing. Heavy grey clouds skidded across on a stiff northerly breeze. They thinned every so often, but barely enough for the sun to shine.
A chink in the cloud cover passed before the sun and light lances appeared. We descended quickly and I managed to photograph Tavo with some light-rays around him. It wasn’t ideal, but I had to take the chances I was given.
The next cenote system was Ponderosa within the Garden Of Eden. That’s what the sign said, but I’m not sure I believed it. It was protected by black gates that warned that anyone ramming them would be liable to pay for the damage, so I had my doubts about the provenance of the area’s name.
However when the sun shines into the water, Ponderosa could be the Garden of Eden. The dive starts on a platform at the large pond’s edge. From there it’s a short swim into the cliff and the entrance to one of the caverns.
The darkness soon surrounded me, closing in on my senses, quickening my heart-rate and tweaking my alertness until I was fully focused. Swimming in an overhead environment is a serious business and takes all your concentration. I wasn’t deep, but I did watch my air, something I rarely do when shallow-water sea-diving.
Ahead the water lightened as we reached an area open to the jungle. We entered in bright sunshine, but clouds had again surrounded the sun and the light was dull.
Tavo and I surfaced. Clouds were not what we wanted. We decided to push on and dropped into a halocline where fresh and saline water mix and it’s impossible to make anything out.

WE DROPPED FURTHER into warmer salt water for a few moments before rising again. For a minute or so we skimmed the surface of the halocline. The rocks an arm’s stretch away were fuzzy and indistinct, yet Tavo’s fins ahead were crystal-clear.
To our right the fissure opened to the jungle again and the light remained lifeless. At the end of the recreational part of the cave, impressive limestone formations sat frozen in time in the darkness.
We turned back and something had changed. Bright light spears descended towards the cenote floor. The sun had emerged and transformed the scene, as the Christmas lights on Oxford Street transform a dull December day.
The whole edge of the cenote was bathed in sun-rays that would have knocked me off my feet had I been standing. My regulator almost dropped from my mouth, because the spectacle was jaw-droppingly beautiful.
I have seen many sights while under water, but this raced into my top ten.
With my air nudging the end of the second third (in cave-diving, air consumption is measured in thirds of a tank – one for going in, the second for coming out and the last for emergencies) we headed back.
The cenote entrance grew brighter until we burst into the sunlit pond, its clear water punctuated by sunbeams.
We edged to the left, where a line denotes the diving area from the swimming area, and I was greeted by a woman’s bare bottom staring back at me.
Thongs are the swimsuit of choice in Mexico. So while I’d just enjoyed the pleasure of the sun, it was a moon that bade me farewell to Mexico’s cenotes.