Cool water works its way into my wetsuit as my guide, Dave Tomlinson, gives the "thumbs down" signal and I descend into the gin-clear waters of Grand Cenote, an inland freshwater cave 130 kilometres south of Cancun, Mexico. Shafts of sunlight shimmer in the open pool. With Tomlinson leading, our group of divers follows single-file into the liquid-filled void. Ahead is only darkness. My eyes slowly adjust to the pale blue light, and the whole expanse of the cave comes into view.
The water is crystal-clear -- I can see a hundred metres or more. Giant columns have formed where stalactites meet the cave floor. I pass through narrow openings with little room to spare. As the cavern fades to black, I flick on my dive light, illuminating alabaster and brown stalactites, hanging from the ceiling like broken icicles and bulbous breasts.
Exploring an underwater cave is exhilarating, unlike anything I have done before. It's an experience that is becoming increasingly popular with many of the 3.5 million visitors to Mexico's Yucatan Peninsula each year. Once an ancient coral reef, the porous limestone bedrock of the Yucatan contains about 3,000 freshwater sinkholes, or cenotes. Many make excellent swimming holes, superb snorkelling sites and offer scuba divers the chance to discover a strange subterranean world. The water is always calm, always clear and there's no chance of getting seasick on the way to the dive site.
I based myself in the town of Tulum on the Caribbean coast, a two-hour drive south of Cancun. Tulum lacks the mega-resorts of Playa del Carmen and Cancun, but is home to many picturesque beach bungalows fronting a near-perfect white-sand beach. My waterfront digs at Azulik Villas were equal parts urban spa and Robinson Crusoe. An hour's walk north along the coastal strip brings you to the Tulum Ruins, a Mayan archeological site perched on sea cliffs overlooking the Caribbean.
To explore the cenotes, I signed up for diving with Cenote Dive Center, a Tulum dive shop run by Tomlinson, a ponytailed 36-year-old from Revelstoke, B.C. Tomlinson has been guiding divers here for nearly a decade. Because I don't have special cave training, I'm required to dive with a guide. There are seven dive-able cenotes within a 10-minute drive of Tulum.
The word cenote originates from the Mayan D'zonot. To the Mayans, cenotes were sources of water, and windows to Xibalba (the underworld). They were magical, sacred places, and were used for human sacrifices. It's easy to see how the Mayans came to think of cenotes as supernatural. When I surface after 40 minutes, I'm in a dazzling grotto with arching entrances at each end.
"How was that?" Tomlinson asks. My group of four divers is beaming from the experience. He then asks to see our gauges, to check how much air we have left in our tanks. We must strictly adhere to the cave diver's "rule of thirds" -- one-third of our air for going in, one-third for coming out, and the remainder saved in case of emergency. As an open-water diver, I am permitted to dive only caverns, which by definition means being within 60 metres of natural light at all times, and I must dive with a guide.
By following a figure-eight route through the cenotes, it feels like you've travelled a great distance into the cave, but in reality you're never far from the surface. Divers follow a set line and must maintain good buoyancy to avoid kicking up silt, which can reduce visibility to nothing. Signs posted in the cenotes show a grim reaper surrounded by dead divers, warning you not to venture off on your own. For those wishing to go further, specialized cave-diving courses are available through Cenote Dive Center. Some of the largest underwater caves in the world are found in this part of the Yucatan, including the Ox Bel Ha system, which is believed to contain more than 140 kilometres of passageways.
The next day, I dive Dos Ojos Cenote, Spanish for "the eyes," so named for two large sinkholes connected by a 400-metre-long passageway. Dos Ojos has more natural light than Grand Cenote -- and, consequently, more divers. Fortunately, most are snorkelling, so I'm able to quickly escape the crowds. The inner chambers have impressive arrays of stalactites, resembling giant candelabras and chandeliers. We surface in another grotto known as the "bat cave," and indeed, I spy a small bat hanging in a crevice in the ceiling.
The following day, I explore Angelita Cenote, a sinkhole resembling a pond in the jungle. My guide for the day is Attila, a young, wavy-haired dive master from Hungary. Unlike the other cenotes, Angelita has no passageways. We drop straight down. At a depth of 25 metres, there's a layer of hydrogen sulfide resembling a cloudbank. A mound of solid ground protrudes through the layer like a mountaintop piercing the clouds. It's covered in dead tree branches, and has an eerie look to it, like a cemetery from a horror movie.
Attila motions for us to drop through the hydrogen sulfide layer. As I pass through, I get the taste of rotten eggs in my mouth. Beneath the layer, the water is clear again, but it's now very dark. I turn on my dive light and explore the bottom at 40 metres. There's little to see, mostly tree branches and dead leaves. At this depth, my time is limited so I soon make my way back up.
After several days of diving, I have begun to notice that there are vast differences between the cenotes. No two are the same. "Every cenote is unique and has its own flavour," Tomlinson says. "There's nothing like them anywhere else in the world."
Pack your bags
Numerous airlines fly to Cancun. Tulum is located on the Caribbean Coast, 130 kilometres south.
WHERE TO DIVE
Cenote Dive Center: 52 (984) 871-2232; http://www.cenotedive.com. The cenotes of Riviera Maya can be dived year-round. Basic open-water certification is all that is required if diving with a guide. Water temperature averages 23 C. Two guided dives cost $125, including equipment. Angelita Cenote costs $160 for two dives.
WHERE TO STAY
Azulik Villas: http://www.azulik.com. Rates start at $290 a night for luxurious beachfront bungalows.
Mayan Temazcal: www.dospalmas.info. Dos Palmas Noche Ceremonial Maya is a local operator offering guests an experience in a Mayan steam house along with cultural exhibits and traditional Mayan cuisine.
For more information on diving in the Riviera Maya, visit rivieramaya.com.