YAX CHEN

THIS SMALLER PROJECT, LIKE 2020’S EXPLORATION effort, started from a well-known cenote called Yax Chen in the southernmost corner of the Ox Bel Ha cave system. The new area introduced some unique challenges to our diving, and the excessive rainfall during this period further complicated the picture for us regarding visibility. Although the team had to wait patiently for conditions to improve, the cave showed exciting possibilities, and the wait to push our discovery to the east-northeast was worth it.

As always, additional data was required, but this time we decided to examine the downstream side of the main opening more extensively. On a regular survey dive, the team discovered the beginning of a new, potentially unexplored area.

Quite early into the survey dives, we managed to reach one of Gary Walten’s end-of-lines from 1997, at a penetration distance of 1.6 km/0.9 mi. The line ended in front of a massive collapse of fallen rocks with just enough space between them for a diver in sidemount configuration.

As always, we wanted to swim in a little bit and check if the tunnel really ended. The strength of the flow was considerable, still flowing downstream into the rubble. As we climbed up the hill between the cracks, a bit of daylight was visible on the top of the pile. We tied in and brought our reel all the way to the crack.

Indeed, it was a cenote, but the way out was very small, even in sidemount, and on top of this, a log blocked our way. We were unsure if Gary or other divers ever saw this daylight source. In our excitement about finding a new cenote, we managed to pull the log to the side and tie it in place with a piece of cave line. We had to get our stages off, squeeze through, hand them to the first diver already on the other side, and put everything back on again.

Cenote Roots

Once we reached the other side, we immediately wanted to drop back down into the cave on the other side of the collapse—but it appeared to be even smaller, so we decided we would follow the flow of the water in the open. Unfor - tunately, the cenote was in a mangrove forest and densely overgrown with roots that we had to cut our way through. After 57 m/187 ft, we reached the overhead again where another line from 1999 was waiting for us. We knew this was another connection between Yax Chen and historic Ox Bel Ha.

The strange thing was that, on this side of the cave—where the line was much closer to the cenote—apparently nobody had thought about traversing it. The cave here was very dark, full of organic sediment, shallow, tannic, and with roots that blocked most of the visibility. Maybe these conditions had discouraged previous explorers from moving on. Because of our challenging experience with the cenote, we named it Cenote Roots. On this side of the cave, we continued our survey, and it quickly became obvious that the east side of the main line here looked open. We decided to check leads here on the following dives.

Preparing for an exploration like this proved challenging at first. Although the distance wasn’t great, a restriction of this size can be a problem. If we wanted to find new cave here, this was the best and closest way through, so we had to get used to the challenge. It was time-consuming to unclip everything, hand all the stage bottles and DPVs through, gear up on the other side, and then continue, but with time, our efficiency improved.

Unfortunately, the first—and most promising— leads to the east very quickly began to die down as we discovered caves filled with dark, fluffy sediment and very irregular tunnels. Navigating more restrictions here did not help, and we tried to take other directions. Often, we were halted after a few months of rainfall that rendered the entire region undiveable due to the shallow depths and accumulation of tannins and hydrogen sulfide.

Slow progress

One of our leads, however, turned more southeast than east, featured a faster-moving flow, and offered improved visibility. After a longer wait, as the conditions slightly improved, we were back to finally check where this new line went.

Unfortunately, after a few hundred meters, our line arrived at another sidemount restriction at about 2.3 km/1.4 mi of penetration. There was seemingly no other way around this one either. Past it, the cave changed in its configuration; it featured more solid, dissolved rock and plenty of collapses. We knew that by following this direction, we could get closer to the sea and maybe even connect to it. With further penetration, the number of sidemount-sized restrictions with an excessive amount of sediment increased.

The progress was slow and tedious—the cave seemed to have open rooms and hidden cracks around every corner, so identifying the best way to push on was difficult. It was also difficult to travel to our closest spot to the sea and, as we neared 3 km/1.9 mi distance from the entrance, we decided to look for a better way. Unfortunately, we were hit by another set of rainstorms, and the conditions worsened. Finally, we decided to dive regardless of the conditions. On the ‘99 lines, the visibility was close to zero. Sometimes you keep going further and further in hope of the conditions improving, but it was not the case this time. However, since we were already there, we thought we would try to explore a better route toward the sea. In almost completely blind conditions, we tried to lay our line—from wall to wall until we hit something and by relying mostly on our compass, which was hard to see, too. After some trials, we managed to establish what seemed to be a decent-sized tunnel that made the travel close to the sea shorter and was also navigable by scooter. This new 300 m/1,000 ft tunnel became the new path of travel after our initial major restriction.

On subsequent dives, we managed to bring more gear through and were able to investigate for longer at our last leads. Despite being so close, we never managed to connect this part of the cave to the sea we were short by about 50 m/165 ft.

After this, when the conditions allowed, we moved to the north, tied some new, shorter lines into our exploration, and—by the end of the season—we had a new, fully connected section of 5.8 km/3.5 mi.

YAX CHEN // DIVE DATA

DIVE TEAM

Wagner, Bjarne Knudsen, and Laszlo Cseh

One new cenote and new connection between Yax Chen and historic Ox Bel Ha