Tunnel visionsDeeply into caves
The thrill of exploring and mapping a huge cave system in Mexico regularly takes experienced US cave-diver Kay Walten under water for more than five hours at a time
I'm toting a tank across my chest to the water's edge like I'm carrying a baby. For this dive my husband Gary and I will need six single tanks, our 15-litre back-mounted doubles and four scooters (diver propulsion vehicles). It's a lot of equipment, but this is going to be a long cave dive. I'm already tired today after driving for an hour in Mexico's summer heat and humidity.Three more miles on a bumpy coconut road finally brings us to our destination the path that leads to the surface pool. As we begin to unload the equipment, my mind drifts to the dive we have planned for today. Five and a half hours of bottom time sounds like a life sentence at this point rather than fun. If it weren't for all the effort so far, I would just as soon turn around and head for home. But having come this far I don't want to call the dive off.
The air feels syrupy thick and hot in my lungs. The mosquitoes are buzzing my head like kamikazes. As the sweat drips from my face, I feel like I could cry, not from sadness but from exhaustion. The day-to-day frustrations of life here in Mexico are wearing me down. I feel like waving the white flag of surrender, yet there's no turning back now. I'll relax tomorrow. Now it's time to don the wetsuit and head in 4000m to the end of the line.
Our project, Yaxchen, is a long chain of caves connected to a number of surface pools (cenotes). Although the cenotes are visible from the air, they're isolated from us by a vast mangrove area that acts as a barrier to our exploration. Flowing fresh water emanating from inland has created both the cenotes and the cave. To date, we've successfully connected 20 of the cenotes through an extensive labyrinth of passages, and in the process explored more than 15,000m of cave.
This cave isn't picture perfect like the ones you see in dive magazines. The stalactites and stalagmites have been eroded away by the passing current and time. The huge cenote pools are green with algae in the summer heat. Some turn red after the rain from tannic acid. The beauty here is an acquired taste.
The surface pools, which are so numerous in this cave system, contain many unusual fish. Schools of tarpon are on top of the food chain in these neighbourhoods, with a crocodile or two making an unexpected appearance. We aren't big fans of open-water diving, and with crocodiles lurking about we're anxious to swim back into the darkness and security of the cave.
To go two and half miles horizontally on scuba with any degree of efficiency takes a lot of equipment and a good bit of practice. We use a system invented by cave divers called double scoot-double staging. We ride one scooter in approximately 1300m while breathing one of the two stage bottles we carry, all the while towing a second scooter.
Then we drop the scooter and tank, pick up a full tank left in the cave on an earlier dive, and pull the towed scooter around in front. With the second scooter we continue into the cave for another 1200m. Finally, we drop the second scooter and stage bottle, leaving us with one stage bottle each and our doubles to use for the upcoming swim. This system only works in Yaxchen because of its shallow depths and numerous cave openings along the route.
The swim is long, 1500m to the end of our last exploration. There we left the end of the line in an enormous cave. A cave so dark and wide that the walls can sometimes not be seen. This dive is stressful. My first scooter seems to be playing up on the way in. The thought of it not working when I get back to it eats at my brain. I try to focus to keep my breathing down. It's so far to the end of the line that each breath reduces the amount of cave we can explore once we get there.
White globs of something drift by in the water column. Both Gary and I telepathically wonder if these might be the underwater counterparts to the cave "snot-tites" that were described in June's National Geographic. More finning again, endless finning. Keep pushing it's like we'll never get there. One hundred minutes into the dive we find the end of our last exploration push. With only 500psi in our doubles remaining from our allotted penetration air, we tie off and swim westward, hoping to find the last two cenotes in our chain of caves.
Gary is leading the push, with me behind to observe the cave around us and look for leads. Within 100m the passageway ends in a room with a small vertical crack too small to pass through. Light from above illuminates the reddish water but there is no way to investigate. This crack is hardly the big surface pool we'd hoped to find.
We regroup and decide to backtrack for 100m to check out the unexplored cenote I spotted on our last dive. This one has a fallen tree on top of a large debris pile that disappears into a milky yellow layer of water. We look at one another and simultaneously wonder if this might be a haven for our reptilian friends. We decide not to surface. Almost time to go, we are close to our thirds rule on air.
Frustrated, we call off the dive and head for home it's 4200m to the truck, dry clothes and something to eat. There were no "high fives" under water, no smiles of success, only looks of defeat after coming so far. I guess every dive can't be great or you wouldn't be able to tell them apart. Three small turtles paddled around one of the surface pools. That gave me a special grin, a reminder of how interesting and special this remote area is. But it didn't elevate my mood.
The scooters are a welcome sight after all the swimming. Picking up our stages and scooter we zoom off. It is 40 minutes, or 1200m, to our next pair of scooters. With 450m to go, the yellow battery-low indicator light illuminates and my speed diminishes. I signal to Gary that my batteries are burning out. He whips out the tow clip and begins pulling the depleted scooter, and me, through the cave. Over the years, this has happened on several occasions. All batteries have their limits. Our deco time is still ticking down. As we approach the next surface pool we rise to 3m of depth. I signal to Gary to tow the scooter I'll swim the 350m to our next scooters, just keeping below the 3m decompression obligation.
Tired and worried about the batteries in my next scooter failing, I pick it up and pull the trigger for the last 1300m home. My scooter runs well. I watch and listen like a hawk for the slightest decrease in power, yet it purrs all the way to our starting point.
We surface exhausted. It was a long dive for only 100m of new cave. After a slow quiet walk to the truck to ditch our tanks we re-hydrate and eat a couple of meusli bars. An hour later we have all the equipment back in the truck except two empty tanks that are still 1300m back in the cave. They'll have to be brought out later on another set-up dive. It's not until we are packed up and headed home that I can finally relax.
Dives like this are not a lot of fun. It isn't until we've had a meal and a good night's sleep that the impact of the dive hits home. Although it wasn't very productive, we're still in awe of this enormous cave. We begin to appreciate the dive not for the new cave we have gained, but for the size and power of these tunnels of darkness.
The image of the sun illuminating large cavern zones, and of these caves that start and stop in lengthy surface pools, has been burned into our memories.
I often feel infinitesimal in this large cave, wondering why I spend my life doing this and wondering, who cares? But I can't stay away. I feel entranced by this cave which has swallowed me whole. The experience of cave exploration is enriching beyond words and sometimes it takes a hard cave dive like this to make you appreciate what has been accomplished. I feel a deep respect for the cave environment and I'm glad that its rewards must be earned, not given.
