Cozumel Underground by Michael Menduno/M2
Cozumel’s Influence in Choosing a Sidemount Rig by Rob Neto

Cozumel Underground

by Michael Menduno
Cozumel, Mexico—While the race to stake-out the world’s longest underwater cave marches on beneath the Yucatan jungle, a handful of explorers have been quietly plumbing the depths of the some of the most unique fresh-water caves in Mexico, less then a hours run away. The trouble is, no one believes that they’re there. Thirty-nine year old financial consultant, Jeff Bozanic, has found it hard to convince others that there are caves in Cozumel. Over the years, Bozanic, who has been exploring the island’s cenotes for more than a decade, has learned to keep his mouth shut.

While attending an international cave diving workshop in Cozumel, Bozanic followed his instincts and shelled out fifty bucks for a jungle horseback ride to check out the mud-red cenote described on a hotel flyer. Getting off at the sinkhole, Bozanic stripped to his briefs, strapped on the make-shift fifty that he cajoled the guide to carry, and slipped into the dark tannic water. Local Mayans thought it was only six feet deep. But they weren’t cave divers. Bozanic descended through the blackness for what seemed like minutes, broke out into clear water at 60 feet, and tied off his safety reel at the top of the large stalactite.
“I hit 120 to 130 feet on that first dive at Xcan Ha, and collected a shrimp and an amphipod, ”recalls Bozanic. “The amazing thing was that when I got back and told others what I found, no one would believe me.” A hundred and twenty feet deep? At the time, the deepest Yucatan caves were less than sixty.

The year was 1987; five years before the term, “tech diver,” was even invented. The sixty to seventy-odd speleo-brethren who attended the New Frontier “Exploring The New Frontier,” organized by the late Parker Turner, were reeling to explore the gargantuan systems being discovered across the channel in the Yucatan—the new underground Mecca. Only a handful of
cavers would ever know, or care, that the specimens that Bozanic had collected turned out to be two new species; the first of more than fifteen that he and his cohorts would discover on the island. Bozanic and company put Cozumel cave diving on the map three years earlier when he noticed a fresh-water halocline while beach diving with his sister off Chankanaab park and followed it back to its source. Two months later, Bozanic and fellow speleo-phile Dennis Williams returned for a week to survey Cueva Quebrada.

“We found thousands of feet of line in the first four hundred feet of cave, if you can believe it—everything from monofilament to clothesline,” recalls Bozanic, who’s considered one of the graybeards in the field. His last dive at Quebrada, required three aluminum eighties in addition to his back-mounted doubles, and lasted almost five hours. Today Quebrada, is the longest of six
major caves on the island, boasting nearly six miles of underwater passage. On to Aerolito Having road-rigged two sets of dual independent eighties, Yucatan explorer/instructor, Steve Gerrard, and I make our way past the four-foot high mound of refuse, empty cerveza bottles and a used pink condom—a local tribute to environmental awareness. Negotiating the slippery embankment, we slide into the emerald green cenote where our guide, Chuck Jones, is adjusting his head-lights. It’s the first time that either Gerrard or myself have cave dived in Cozumel.

We take turns leaning back in the 72° F water for a bubble-check. I’m fizzing—one of my DIN adapters is refusing to mate with the Dali-esque valve on my battered Cozumel renta-tank leaving a tell-tale bubble trail. Jones peels off an o-ring from his watch band, and proceeds to save my dive while launching into his briefing. You can tell he has done this before. Located near Caleta marina, in the area slated for the ‘reef-eating’ cruise ship pier and more shopping malls, “Aerolito de Paradiso,” is one of the most “bio-active” caves on the island, with more than 20,000 feet of surveyed passage from thirty to over 100 feet deep. Like the nearby reef, its future is clouded by possible development.

Underground film-maker, Wes Skiles, was the first to map out the cave for a hydrology report in 1986. Five years later, Jones started swimming the system, and added nearly 3000 feet of line. Our goal today is to make the half-hour swim to the Dome Room, a huge water-filled chamber, 350 feet in diameter, eighty feet from ceiling to floor, about 1600 feet back in the cave.
Bubbles in check, Jones finishes the briefing and we submerge. Chuck Jones is a member of the Cozumel underground in good standing. A computer nerd by trade, diver by avocation, Jones first dived Cozumel in the seventies, and then moved to the island nine years ago. His friends thought he was nuts.

Like cave diving, making a living in the dive business is a matter of survival. Jones survived in order to feed his passion for virgin passage. This year, in response to cyber-island economics, Jones decided to go into business for himself, and put Cozumel on the net. Like Bozanic, the forty-five year old Jones can attest to the unique hazards of Cozumel cave diving. Last summer, he and five other volunteers got caught in a Mexican cross-fire between the Federalies and local INAH (Institute for Nautical Anthropology and History) officials while recovering submerged Mayan pottery under the supervision of a museum archeologist.

The cenote was slated to be buried under a local housing project. For their efforts, Jones spent four days in jail before the Mexican court determined that INAH hadn’t done the proper paperwork. Jones and the others were released only to be flamed on the net by state-side cavers who didn’t know the whole story. Retorts Jones, “Cave diving community is an oxymoron. I still do cave and caverns tours and teach, but these days I watch my back.” Dome Room logged, Gerrard, Jones and I finish debriefing over a three-dollar dinner with sangria, at a neighborhood eatery. If the price didn’t give away the local nature of the establishment, the three brightly-painted young hookers having their breakfast at the table next to us, did.

Jones recently got back from his first fly over the island paradise to scout out new cenotes. “Talk about information overload, I was bowled over. I had two cameras, one with a 70 mm lens, and couldn’t shoot film fast enough, reports Jones. “ All I can say is that there are a lot of cenotes on this island.” And no one even knows that they’re there. Jones is emphatic, “We need more cave divers; it’s the only way to create the pressure to find more caves.” And protect the ones that are there.

Michael Menduno/M2

First printed in Aquacorps Magazine in the early 90s. Reprinted with permission.

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Cozumel’s Influence in Choosing a Sidemount Rig

by Rob Neto

It was 11:32 a.m. on June 8, 2014, when my buddy and teammate David Dewberry and I began our descent on the western shore of the island of Cozumel. Over the next two minutes, we swam out toward the first reef and one of several openings to Sistema Dos Coronas, a cave system that requires a sidemount configuration, and is, in my opinion, one of the most beautiful underwater cave systems in Mexico. We began our penetration into the system with the hopes of finding a connection to Cueva Quebrada, a larger system that is situated adjacent to Dos Coronas. We hoped this dive would finally complete what we had been working toward:  connecting Sistema Dos Coronas to Cueva Quebrada. Over the previous three years we had traveled to Cozumel every five to six months to explore and map Sistema Dos Coronas. Up to that point we had explored and mapped over 2,300 meters (7,000 feet) of passage. 

About a year and a half before this trip, David and I assisted German Yanez, a cave diver and instructor living on the island, with re-lining a couple of passages in Cueva Quebrada. Due to strong currents and halocline, the line in Cueva Quebrada weakens and deteriorates fairly quickly. We had brought gold line with us in hopes that it might hold up longer than the previously used line (about three years). As we pulled on the existing line during previous dives, it would break into pieces in our hands. It was sobering to think that cave divers relied on this line to exit the cave. After the line replacement, we realized our exploration efforts in Sistema Dos Coronas had pushed us very close to the very passages we relined in Cueva Quebrada. I obtained some preliminary survey data on our exit, plotted it out, and made an overlay which confirmed the two systems were close; in fact, they were within 100 meters (300 feet) of each other.

Before we had this information we had been pushing a passage in Sistema Dos Coronas heading south. The passage had already reached a penetration distance of over 700 meters (2,100 feet) and was getting smaller. We had encountered a few restrictions, but we were able to negotiate these fairly easily with the gear configuration we were in. However, the restrictions we saw ahead were even smaller. But because we could easily see that the passage beyond these restrictions opened up we were determined to push beyond them. In the process it became apparent to us that the sidemount rigs we had been using, the same ones we use when diving Florida caves, were not the optimal choice for this system. So, we began researching sidemount rigs in hopes of finding one better suited to this environment.

Sidemount is more than a configuration: it’s a tool that has to be adapted to fit the job at hand.

A quick review of sidemount configurations across the world reveals some apparent differences based on geography. North Florida cave divers tend to use larger sidemount rigs with horseshoe- or donut-shaped wings with lift capacities in the 22.7 to 27.3 kilogram (50 to 60 pound) range. Mexico cave divers tend to use smaller rigs with trapezium-shaped wings with lift capacities in the 9 to 13.5 kilogram (20 to 30 pound) range. European divers use a variety of rigs dependent on their region, but most have lift capacities in the 20.5 to 27.3 kilogram (45 to 60 pound) range. In Europe we also tend to see smaller rigs with larger, rectangular shaped wings or rigs with the wing sandwiched between two backplates.

While there are some sidemount rigs that can be used in all environments, they are usually not ideal for all environments. Among North Florida cave divers we tend to see sidemount rigs with more lift capacity. This is partly due to steel cylinders being a popular choice in this region and   because many newer divers wear wetsuits while diving in the relatively warm 68 to 72 degree Fahrenheit (20 to 22 degree Celsius) waters. This combination, however, is not ideal because wetsuits don’t have enough positive buoyancy; they compress; and in the event of a bladder failure provide no redundant buoyancy (e.g., a drysuit). Nonetheless, the combination is commonplace. In Mexico, water temps are 10 degrees Fahrenheit (5.5 degrees Celsius) warmer and divers can use less exposure protection. The cave systems in Mexico are, for the most part, shallower than those in Florida, so the lower volumes of aluminum cylinders are acceptable. The lighter cylinders mean not as much lift is necessary and the thinner wetsuit means less buoyancy change resulting from suit compression.

When a drysuit is added to the equation, things change. For example, my standard Florida sidemount rig has 15 kilograms (33 pounds) of lift. With a drysuit, that is sufficient to offset the negative buoyancy of large steel cylinders with multiple stages plus 3.6 kilograms (8 pounds) of lead. In Mexico with a 4 mm neoprene suit, four aluminum 80 cubic feet (10.5 liters) cylinders, and 1.8 kilograms (4 pounds) of lead, only 10 kilograms (22 pounds) of lift is necessary.

So, why not use the large rig in both locations? That is an option, and in fact, is what we did for the first couple years we explored Sistema Dos Coronas. However, because that much lift is not necessary and can actually be a limiting factor while trying to negotiate some restrictions, it’s not the optimal choice.

Sistema Dos Coronas has a small entrance measuring about 6 meters (20 feet) wide by 2 meters (6 feet) tall. About 21 meters (70 feet) from the entrance we encounter our first restriction requiring sidemount. With my Florida rig I could get through the restriction with both sidemount cylinders in place, but had to remove my stage cylinders and push them ahead of me. There were two further restrictions in the first 200 meters (600 feet), one a low bedding plain about 12 meters (40 feet) long that required stage cylinder removal as well.

Following this restriction the passage morphs into one of the most beautifully decorated passages ever seen: thousands of meters of passage with untouched, pristine speleothems in some areas and what appears to be petrified coral in others. Both can also be found together in many areas of the cave. Some of these speleothems made it very difficult to move farther into larger going passage. So the search for a smaller rig began.

I had a smaller harness sitting at home that was designed by a Mexico cave diver that I had yet to use because I hadn’t yet found what I considered a suitable wing for it. As I mentioned earlier, sidemount divers in Mexico tend to prefer a different shape of wing than those in Florida. The reason for the difference is that when more lift is needed manufacturers try to spread the gas over a larger area to keep the rig more streamlined. Less lift doesn’t require as much gas (hence area), so a square or rectangular wing works well. Unfortunately, because manufacturers want to accommodate as many potential customers as possible, wings tend to be larger than they really need to be. I didn’t need a wing with a lot of lift, so my choices were limited.

One day I was diving with a friend who was using a buoyancy device with 4.5 kilograms (10 pounds) of lift. This device had not been designed as a primary lift device, but seemed to work well for warmer water diving with aluminum cylinders. I purchased one of these and began using it with the smaller harness in Cozumel. It ended up working out well with three aluminum cylinders and no additional weight.

The restrictions for which I previously had to remove my stage cylinder to get through no longer required cylinder removal. My larger Florida rig, although streamlined, was just bulky enough to make that configuration too large, while this new rig was low enough in profile to allow me to get through many of the restrictions with my sidemount cylinders and stage cylinders in place. It also allowed me to pass through other restrictions that had once required me to remove a sidemount cylinder without having to remove it. What this meant was that I could now get through smaller restrictions with minimal impact on the area. I made a similar rig for my buddy and we were soon pushing farther into the system than we had been able to on previous occasions, including that southbound passage. We were able to extend the end of the line in that passage an additional 100 meters (300 feet) before our focus changed. 

Focusing on the proximity of Sistema Dos Coronas to Cueva Quebrada, we started hitting both systems in the areas that lined up closest to each other. We found ourselves moving through restrictions so small we would never have been able to get through them in our Florida sidemount rigs. The new, smaller rigs paid off.

One of the passages we found on the Cueva Quebrada side we appropriately named the Grinder. It was given this name because we have yet to go through that passage without losing or breaking gear. We’ve lost wet notes, jump spools, even broken a stainless steel belt buckle. The passage literally grinded grinds the gear off of us. Part of the reason is there are protrusions sticking out that grab onto the material of our rigs. There is no way the larger rigs would have even fit. But it’s this passage that we kept coming back to on the overlay and we knew we had to be missing something. In spite of the small size of the Grinder, we made quite a few dives to that area.

The area of the Grinder is about 7 meters (24 feet) deep while the adjacent area in Sistema Dos Coronas is 9 meters (30 feet) deep. We still had a lot of rock to get through. But there were areas beyond the Grinder that sloped down to about 8 meters (26 to 27 feet) in depth. They just pinched down too small, even for our new smaller rigs.

On one of our last dives in that section I noticed a small area off to the right as I headed in there once again to make sure we hadn’t missed anything. I marked it with a clothespin and on the way back decided to give it a look. I ran about 40 feet (12 meters) of line before coming to a small hole in the floor. I dropped down into that hole as far as I could and saw a small passage that continued on to my left, but I couldn’t tell if it opened up and definitely couldn’t see any line in it. I decided I didn’t have enough gas at that point in the dive to comfortably negotiate a restriction that small, and we would have to come back with that as the objective.

Later that day I plotted the survey data I had collected and saw that the passage we had just found headed right toward Sistema Dos Coronas, and in fact, it now looked like it was only a few feet from overlapping one of the passages on that side. The next day we went back to Sistema Dos Coronas and headed straight for the passage we believed should connect. We didn’t have high hopes as we had been in there before, but were wishful that maybe we missed something. About an hour after we had started the dive, we approached the end of the line in the passage of interest. I remembered putting that line in the year before and tying it off just before a small restriction that looked like it might go, but there was no way I would fit (in the Florida rig I wore at the time) and I hadn’t been able to see the larger passage beyond anyway. The end of the line was tied off to a limestone protrusion to the side just before the restriction, and when we looked into the restriction we saw our line from the day before just over 10 feet (3 meters) away. We had found the connection!

I pulled a spool, tied off to the end of the line, and removed one of my cylinders to push it ahead of me. I had no doubt that with the smaller rig I was wearing I could fit this time. It took a couple of minutes but I was able to negotiate that last 10 feet (3 meters) to tie the two lines together. Now for the difficult part: getting back out of the restriction. It took almost ten minutes to turn around and get back out to the larger room where the end of the line had previously been, and where my buddy David patiently waited. The restriction was small with limestone protrusions sticking out from all sides. Backing out was not an option because there was no way to see which way to contort or position my cylinders to exit. By the time I made it out to the larger adjacent room, the webbing on my rig had been pulled in several directions and I had to exit with a lopsided rig. But this wasn’t really that big of a deal to me after our discovery.

At 1:29 p.m. that day we surfaced, two of the happiest cave divers. More than two years of effort had finally paid off. Connecting Sistema Dos Coronas to Cueva Quebrada brought the length of the longest cave system in Cozumel from 8,839 meters (29,000 feet) to almost 11,582 meters (38,000 feet). It brought the maximum depth from 9 meters (29 feet) to 17 meters (52 feet), and added three more openings to Cueva Quebrada. This is what cave exploration is all about. 

We had started the exploration using the rigs we owned and with which we were familiar. Initially, they worked, but as we eventually learned, they were not optimal. They provided a harness to attach cylinders to and (more than) enough lift to offset our negative buoyancy. But they were simply too much rig. Cave systems in Mexico are much more decorated than those in Florida. For us, and this particular system, this meant we needed our rigs to be as streamlined as possible. This isn’t to imply there aren’t small restrictions in Florida caves, but the conditions in Florida caves require more lift, which means less streamlining.

There isn’t much of a functional difference between the two rigs we dive in Florida and Mexico. Low pressure inflators are in the same location, D rings are in the same location, and gear is stored in the same place. The main difference is the exhaust valve for the wings. On our Florida rigs it is located on the shoulder, and on our Mexico rigs it’s located on our hip. Other than that, the transition from one to the other is seamless, and choosing the proper sidemount rig for the diving we did enabled us to achieve a great long-sought after goal.

Rob Neto

First printed in Quest Diving Magazine in 1st quarter 2016. Reprinted with permission.

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