It´s a good thing my husband isn’t a jealous man, because I was following Antonio like a hound on the trail of a rabbit, and I wasn’t going to let him out of my sight. Antonio, a tall, strong Spaniard with soft, brown eyes and a thick accent, was the dive master leading us on an underwater journey through the ancient and sacred Mayan underground cavern Dos Ojos, in the Yucatán Peninsula of Mexico. I was freaked, and he was my rock.

"What do you mean, we will be carrying flashlights?" I interrupt Antonio as he prepped us on the details of the dive site, my eyes wide with fear. Then, it starts to sink in, the caverns are dark inside. But how is that possible? I ask myself, embarrassed now to be revealing my fear. I’d seen pictures of wide-open spaces with plenty of light showing off gorgeous stalactites and stalagmites. Of course, the openings were the areas photographed, but as divers we would explore deeper, darker tubes and passageways. Ay ay ay. I wasn’t so sure I could do this.

But we were already barreling down the impeccable four-lane highway in the Riviera Maya south of Cancun and Playa del Carmen on route to the cenote – seven divers, two dive masters, and a load of gear. I try to console myself thinking about the beauty of the photos I had seen, but Antonio keeps revealing more frightening tidbits about the dive that make my heart beat fast and my mouth go dry.

"You must be very aware of your buoyancy so as not to stir up the silt at the bottom or hit any stalactites over head, always maintaining your body in a horizontal position," he warns.

The dialog inside my head grows to shouting volume. What?! Stalactites overhead! Are the tunnels completely submerged?

I couldn’t help myself and blurted, "You mean, we can’t come up inside the caves and find air?" The flicker in Antonio’s eye lets me know that I am making him a bit nervous about diving with me, but he maintains his cool. He reassures me that we could wind our way out and reach one of the various open areas within in a matter of one minute, if necessary.

The briefing continues. It is the most detailed pre-dive speech I have ever heard, which makes me more and more agitated. The final touch that nearly pushes me over the edge into retreat is that we will have to swim in single file, as some of the passageways will not accommodate us side by side. Even worse, we might encounter another team of divers trying to squeeze through at the same time. I imagine the cramped space, the inability to surface, and the darkness. Panic warms the skin of my face. I spend the rest of the ride silently trying to control my thoughts, focusing on the confidence and experience Antonio exudes.

Dos Ojos (Two Eyes, named for its double circle shape) is one of many cenotes or underground river systems in the Yucatán, which over the centuries developed into immense caves and caverns and formed an essential part of the Mayan spiritual world. A few are visited by recreational divers, and some are explored by more specialized cave divers. By definition, a cavern is a formation in which points of light indicating an exit to the surface are always visible, no matter how far in the distance. A cave, by contrast, is a truly deep tunnel, where it is a must to tie ropes at the entrance and along the way, and the darkness is absolute.

Fortunately, I am an experienced diver. I am not afraid of going under the water, just going into a small space. Antonio soothes my nerves by reminding me that most people feel nervous in anticipation of this unknown, but then find that it’s easier than they expected. The dive is a shallow 34 feet at the deepest point, and he will be right in front of me.

I trust him. I push myself. I contemplate the ancient Mayan people and their rituals to distract my mind. I focus on the cave’s walls and internal structures. It is awesome to think that it takes a century for a stalactite to grow half an inch! And Dos Ojos is chock full, some even form thick columns extending 20 feet from ceiling to floor. We follow the path of a rope, permanently marking the route for divers. My breathing slows as I realize it is, in fact, wide open inside.

There are certain passageways where we squeeze between the rock formations, but the space and volume of water around us is large, even in the relative darkness. I look back towards the entrance, which is fading with the distance but appears mysterious with its jagged outline encircling the turquoise light from outside. This is where the photographs I had seen were taken, which I assumed were from the cavern’s depths.

It’s easy to see why we were warned about the bottom. With even the slightest touch, fine particles on the cave’s bottom swirl like tiny tornadoes, reducing the visibility. We are careful to maintain perfect buoyancy, using a single finger to propel ourselves forward where necessary rather than kicking. We had been asked never to use a regular kick, but only a frog kick or an occasional finger on a rock for support.

It’s cold. I am wearing a full length wetsuit and a shorty on top, but as the heat of my anxiety starts to wane, I become aware of the frigid 75-degree water temperature. We follow the internal passage along the rim of the first eye-like underground circle. One of the rules with this site is that divers must be headed out of the cavern when they reach 2000psi on the air gauge, accounting for 1000 pounds to go in, 1000 coming out, and 1000 as a reserve in a 3000psi tank. But because we swim in a circle, it’s important to go with a guide who knows the place and can judge if the halfway point has been passed by the time the first diver is down to 2000 pounds, or if the group will need to turn around and retrace the route to the entrance.

After the halfway point, about 25-30 minutes into the dive, we surface in a large open place to appreciate the beauty afforded by the natural light filtering in on the cavern’s walls and on the fresh water we swim in. Antonio tells us the exit for the first loop is about 12 minutes out, and advises us to keep our eyes open for ancient bones and fossils in the walls. As we proceed, he picks a few bony pieces off the floor and shines them with his flashlight for us to see.

When we reach the mouth of Dos Ojos, we quickly change out our air tanks and jump in again, anticipating what is supposed to be a slightly shorter route, but even more amazing than the first. By now I am completely relaxed and enjoying myself. I feel proud to have conquered my mind’s deep-seated fears, and in awe that I am able to actually do this dive. Triumph!

The promise of beauty held true as we gracefully undulated up, over, around, between and through the rock structures that were once living and growing, but for some time had been flooded by the sweet waters of the underground spring that fed the ancient river. Toward the middle of the dive, this time, we surfaced in The Bat Cave, a big and relatively dark cavern where tiny bats hung all over the ceiling. By now, most of us are shivering in the cold water, and the German-speaking diver complains that it feels colder than the icy waters near his homeland.

During the final piece of the dive, we spot two odd fresh-water shrimp walking on the silty bottom. Besides these shrimp and the occasional tiny fish, we don’t see any animal life. By contrast to ocean diving, the thrill here is to observe the place itself and its formations, and of course, to accomplish an out-of-the-ordinary feat.

When we got out to warm up in the sun and eat a sandwich, I was beaming with pride and accomplishment. We all dozed on the way back in the van, finally relaxed. And when I said my goodbyes to Antonio it was with sincere gratitude. I won’t easily forget the confidence in his soft, brown eyes.