Tripping the Dark Fantastic
  An Overview to Recreational Cavern Diving in Mexico

There are few places in the world where recreational level divers can safely experience the wow of cavern diving.
The Yucatan Peninsula is one of them.

Angelita Cenote
Dos Ojos Cavern
Chikin Ha Cavern
Ponderosa Cavern
Cavern Diving Slideshows
Cavern Diving Image Galleries

Yucatan cavern diving country, at least for recreational divers, is located around Playa del Carmen, and runs as far south as Tulum. The ocean diving in this area does not compare to the fantastic diving just a few kilometers across the water at Cozumel.  Nevertheless, there are numerous dive operators in both Playa del Carmen and south near Akumal, as well as on Cozumel, who offer cavern diving excursions along with ocean diving.  There is also an abundance of hotels and resorts from which to choose in and around Playa, as well as south along the Riviera Maya.  Some dive operators will come and pick you up where you are staying.  Others will require that you meet them either at their dive shop or at a pre-determined place.  A cavern diving day trip from Cozumel is also quite simple.  Do your homework and planning in advance, and the whole thing is pretty darn wonderful.

History

The entire Yucatan Peninsula is formed of limestone. Several times in the geologic history of Earth much of the peninsula was above the level of the ocean.  At other times, after ice ages, the area was below sea level.  Limestone is by nature porous stuff.  Rain water leached through the limestone over the millennia, during the eras when the water level was low. That dripping of groundwater created mineral deposits, which over time became caverns full of stalactites and stalagmites, some of which are quite immense. Then much of it was frozen in time during the rise in sea level following the last ice age, about 18,000 years ago, when the deeper dry caves flooded. Personally, I was quite taken by that part of the experience. There were moments when I had an intense feeling of looking back in time. I could imagine ancient peoples living in some of those caves.  And it boggles the mind to think how many cavern/cave systems in the Yucatan are, as yet, unexplored: when you fly in to Cancun, for as far as the eye can see, there is a stretch of flat forest springing out of limestone. You can bet it is a swiss cheese full of possibilities.

By definition, a cavern is a cavern and not a cave because natural light can be viewed from any point in the dive, which effectively means that there is an escape hatch no more than 100 feet or so away. Yeah, right ;^)   Really, these are caves with occasional windows. In my experience, there were some pretty dark bits, especially in the Dos Ojos system, but then again, we were not encouraged to turn off our lights to see where the natural light was (a big no-no in cavern diving, for good reason).  But where there was no daylight, I did see that there were some underground dry caves above the water’s surface.

Cavern Diving Day Trip from Cozumel

Making a day trip to the caverns from Cozumel is no biggie. Most of the larger dive operators on Cozumel can arrange your cavern dives with operators with whom they have reciprocal arrangements on the mainland. For instance, when we dove with Deep Blue on Cozumel, they had an arrangement with Yucatek on the mainland. You can also prearrange your dives before leaving on your holiday by contacting one of the many dive operators in and around Playa del Carmen that offer guided recreational dives. I have been diving with both Tank Ha and Yucatek, and despite some minor quibbles, my experience was that both of these operators offer a safe cavern diving experience, for experienced divers.

Expect to pay about US$100 pp for a two tank cavern diving excursion. Some specialty dives, such as La Angelita, may cost a bit more, due to driving distance. If you are traveling from Cozumel you will need to add on the cost of a ferry crossing (~US$19pp round trip), plus usurious cab fares if you are staying outside of San Miguel. Currently the cab fare from Iberostar and Allegro at the south end of the island to the ferry dock in San Miguel is US$19 each way. Tipping is also expected by dive guides, van drivers, porters etc.

The dive operator you use will be able to advise you as to the best ferry to catch in order to meet up with your dive guide for the van ride to the caverns. One other option is to rent a car or flag down a taxi on your arrival in Playa del Carmen, and head down to Hidden Worlds (about 25 mins south of Playa), which will take you on the famous Dos Ojos cavern dives of IMAX infamy. Pre-booking is strongly recommended.

About the Cavern Diving Experience

The caverns in which I have been diving thus far are generally quite spacious, especially Ponderosa and Chikin Ha. The caverns are generally filled with crystalline fresh water to about 35 feet or so, which can mean phenomenal visibility. In some of the deeper caverns divers experience the oddity of a halocline – a distinctive demarcation where the fresh water sits on top of the salt water below it. It makes for all kinds of neat effects (some reminiscent of 60’s flashbacks ;^) when the two waters mix as divers disturb them. It was especially groovy with rays of sunlight refracting through the millions of prisms that the stirred-up water creates, but also a tad discombobulating to experience such tremendous visual distortion.

The caverns are accessed by cenotes (little fresh water oases), which were formed when cave roofs collapsed, leaving open pools in the jungle.  Getting to the cenotes can be an adventure in itself, especially after heavy rains, when what little leveling of road that had been previously accomplished is washed out.

On my first cavern dives I dove with Tank ha, based more on convenience (while their main shop is in Playa, they also have a branch shop set up at Club Robinson Tulum, where I was staying), than for any other reason. I was not disappointed by my dives with them, and the convenience of not having to schlep my stuff into town to get aboard a Playa del Carmen-based dive shop’s mini-van-ride-from-hell down a Mexican frightway made it worth the fees: US$55 for a one tank cavern dive, US$100 for a two tanker at Dos Ojos.

There are at least eight caverns presently open to non-certified cavern divers. Claudia, one of Tank Ha's cavern gurus, er, guides, told me that they are all great – and unique. She is a German dive instructor (DIR all the way - it took her a while to get over my danglies ;^), who has worked and dived her way around the world, only to plant herself in Mexico. She is the über cave diving fanatic – you know, the kind who gets a special little light in her eyes whenever she’s talking about it. She is hooked.

All recreational level cavern dives are led by cavern-certified dive guides like Claudia.  I personally would not follow anyone into the caverns who is not rigged with double tanks and a long donor hose. I also believe that it would be the makings of a Darwin Award presentation to attempt to dive these labyrinthine caverns unguided, unless you have the appropriate certification level, and the appropriate equipment, and the appropriate experience, yada yada. For that stuff, you need to take some serious cavern certification (i.e. GUE courses).

As it is, the recreational cavern diving experience is intended for "experienced" recreational level divers.  These dives take place in overhead environments, and a cavern is no place for a freak out or an air hoover.

There were lines that were run through all the caverns I have been diving in, except at the beginning of Ponderosa, where Claudia ran her reel to hook up with the one inexplicably anchored farther in.  The dive guide follows the lines, and you follow the dive guide, in single file.  Divers must use a fins up technique in order to ensure that the wash from the propulsion of their fins is directed up to the roof of the cavern, as opposed to down to the fine silt bottom that is so easily disturbed.

Diving in the caverns requires divers to strictly adhere to the rule of thirds. That is, one third gas out, one third for the return (assuming reverse course) and one third in reserve for contingencies. Dive guides will turn the dive when the first diver in your group reaches one third of their tank capacity. Look for a good fill as you set up. A 3000 PSI fill will turn at 2000, a 2700 PSI fill will have to turn at 1800. As long as you are not burdened with gas guzzlers in your group, you can expect the dives to average about 45 minutes.

Precision buoyancy control is also a must.  Uncontrolled upwards movement will cause a diver to hit the beautiful, and delicate, formations, possibly sheering them off.  Once they are gone, they can never grow back.  Uncontrolled downwards movement will cause the diver to make contact with the bottom, which is very fine limestone dust.  Stirring up that dust is not a good thing.  It is difficult to follow your dive guide and/or find the line showing the way out when you can't see either of them =8^O   Divers should also take great care to ensure that all of their gear is streamlined and tucked up - I saw one diver ahead of me with a dangling octopus snag the guideline and just about break it. Yikes.

In June the water temperatures were approximately 78F for the fresh water, and 80F below the halocline in the salt water. In November, the temperatures were a few degrees cooler for both. Insulation is a personal thing. I chill quite easily, but was very comfortable wearing a 3mm full with a 2mm hooded vest underneath on both trips. Booties are also a good idea - the paths leading down to the cenotes are quite rocky. If you are diving full foot fins, I would recommend wearing a pair of inexpensive sneakers or water shoes, and stowing them somewhere out of sight while you are diving for retrieval on your return. Theft can be an issue at cavern diving sites - most of them are quite remote. It would be extremely unwise to leave any valuables in your unattended car or van while you are diving.

Mosquitoes are a major problem in the jungle. I would recommend either wearing a lycra dive skin while you are there, or covering up in some other way. DEET works, but shouldn't be worn prior to your dive(s) because of water contamination issues.

Some dive operators provide snacks, bottled water etc. It wouldn't hurt to bring your own to be sure you have adequate hydration and energy supply.