COKA HA EAST

AFTER THE EXPLORATION IN YAX CHEN , it was time for a change of scenery—the team was ready to focus their efforts in other places for a while.

Bil Phillips originally found and explored cenote Coka Ha in the early 2000s, and it is in the heart of the Ox Bel Ha cave system. Huge freshwater tunnels, dark cave decorations, and lots of percolation characterize most of this area.

In 2019, the team had access to the cenote and re-surveyed a massive and very defined passage going straight toward the east with a decent amount of flow. After numerous unsuccessful attempts to break out of this tunnel, either to the north or south, the team took a southeast turn toward the end of the line, following the water. As a result, they discovered two new cenotes (later named Muuch and Ookol) and a few open leads.

When the team suddenly lost access, the divers had to move to other exploration areas.

The team was still mulling over further possible paths from the new cenotes to the east, but the lack of direct access to the sinkhole complicated matters.

After finishing some other projects, the divers had time to return here in early 2022. But, they used cenote Chuup Ich as an entry point—about 2.6 km/1.6 mi north of Coka Ha. This added a considerable amount of travel, not counting the entirety of the east tunnel next to Coka Ha.

After checking survey data and making some calculations, the divers identified the current end of line at 4.1 km/2.5 mi from Chuup Ich. Prepared with special batteries for the DPVs and having enough experience and knowledge about the area, the team decided to initiate regular longer dives downstream from the entry point.

Bat cave

Luckily, 90% of the travel was comfortable— despite being fully overhead—with quite a lot of navigational points and a few restrictions along the way. The team encountered one major restriction at a penetration distance of 3.6 km/2.2 mi but found a more navigable bypass tunnel nearby.

On the first dives, the team made good progress pushing the cave further to the east, hugging the east wall of the cenotes and dropping a bit deeper. After some irregular, small, and silty tunnels, the cave opened back up again into its regular size, where dark decorations loomed and the eastern water flow picked up again. Unfortunately, this only lasted for a couple hundred meters, at which point the cave hit a steep, silty slope with organic sediment. Swimming to the top, the divers found a small dry cave inhabited by bats and with a small source of light on the opposite wall. The divers named this little room “the bat cave” for future reference.

Initially, it seemed there was no way around the bat cave, but on a subsequent dive, divers discovered a drop down to the northeast next to the bat cave and continued in that direction. They hoped that this tunnel would loop around the bat cave, ascend a bit, and continue going east.

Once the cave took a northeast direction, the ceiling descended at the same time, and percolation followed the divers even more aggressively. The challenge in this area was to work as rapidly and efficiently as possible since there were only moments of visibility available for the first diver. If one lead wasn’t identified well, or took too long to check, we were looking at another 4.5 km/2.7 mi of travel for our next dive. Little by little, the team made good progress, but the cave never returned to its original depth and direction.

The cave was pushed further from this point in multiple directions, but all the leads became increasingly small or ended in a collapse. This area of the cave seemed to end close to 5 km/3.1 mi from our original point of entry. On the last dives, the team checked closer leads, but neither of them significantly deviated from the main east direction. Perhaps they are a side effect of the massive water flow straight to the east.

The shallow depths of Mexican caves allow us to penetrate longer on opencircuit configuration.

COKA HA EAST // DIVE DATA

NEW EXPLORATION DISTANCE 3.2 km/1.9 mi where 2.1 km/1.3 mi creates its own connected section

AVERAGE DEPTH 11 m/36 ft

MAX DEPTH 19.5 m/64 ft

EQUIPMENT OC GUE backmount and sidemount configurations with multiple stages and SUEX DPVs

LONGEST PENETRATION 5 km/3.1 mi

AVERAGE BOTTOM TIMES 6-7 hours with minimum decompression

DIVE TEAM Emőke Wagner, Bjarne Knudsen, and Laszlo Cseh