The Mystery of the Cenote Odyssey Incident: Exploring the Depths of an Underwater Cave

Incident Location	Diver Full Name
Mexico, Tulum, Yucatan Peninsula, Sistema Ox Bel Ha	Unknown

On April 23, 2022, a meticulous Russian diver went for an exploration dive into the Cenote Odyssey. His ongoing survey project in this cave has brought him more familiarity with the cave system. However, on this day he got himself into trouble and left the cave diving community with many unanswered questions as regards his exploration in the deep.

The Cenote Odyssey

A major part of the Ox Bel Ha cave system is the Cenote Odyssey, located south of Tulum, Quintana Roo, Mexico. The average depth of the cave is about 40 ft (12 m), with the downstream flowing towards the ocean. One of the subsystems of Sistema Ox Bel Ha is the Naranjal. Some time ago, three prehistoric human remains were found within this subsystem.

The bones of a woman of about 18 to 20 years old, Eve of Naharon, were discovered at a location around 1,207 ft (368 m) away from the Jailhouse cenote entrance. The second was the bone of another woman, about 44 to 50 years old, found at a location around 1.2 miles (2 km) away from the Jailhouse cenote entrance. The third set of bone remains was found in Muknal Cave, part of the Naranjal Subsystem; it belonged to a man of about 40 to 50 years old, the Muknal Grandfather.

The Muknal Grandfather shows evidence of secondary burial, which was different from the way the other two bone remains were found. The result of the analysis of these skeletons shows the possibility of Ox Bel Ha being used as a prominent site for ritual burial in ancient days.

The Missing Diver

On April 23, 2022, a 32-years-old Russian cave diver went to Cenote Odyssey. He was an experienced cave diver who had certifications in a full cave, stage cave, and diver propulsion vehicle (DPV) cave diving. He was an active diver in this area; he spent the last two years diving in the Ox Bel Ha cave system. He organized several cave diving training sessions and spent time surveying different caves.

His passion as a diver made him spend all his life exploring caves rather than just diving for the fun of it. He was a remote programmer. His ongoing survey project in this cave has brought him more familiarity with the cave system and the locals in the area. He had performed between 300 – 400 cave dives. His dive started around 10 a.m.. The people who worked on a building site close to the cenote saw him entering the cave.

During the afternoon, they became very concerned when they haven’t seen him return. At first, they assumed that he had some delays, so they were patient for some other hours, but he still didn’t show up until the evening. Then they raised an alarm about the missing diver. They first called a local diver, but later sent the news throughout the whole community to gather more people to help them search for this diver.

Initial Search Efforts

Fortunately, divers from different places like Playa del Carmen, Puerto Aven-Turas, and Tulum came to the accident scene, and they went into the cenote for the first search. Three divers, Lanny Vogel, Kim Davidsson, and Peter Broger, were members of the first search team. They started their search in the middle of the night, just a few minutes before 3 a.m. on Sunday.

Robbie Schmittner, Alessandra Figari, and Hitoshi Miho were around as surface support for this first team. The complexity of the system and the number of lines in the cave will not allow for random searches, so they had to retrace the steps of the missing diver without knowledge of his dive plan. Each member of the search team used a side-mount configuration, an extra-stage tank, and a DPV.

They searched different parts of the cave but could not find him. However, their efforts were rewarded when they finally found the missing diver. He had made three jumps starting from the entrance, using line markers. The navigations he made were appropriate and consistent according to the safe cave diving rules and protocol.

His body was found around 700 ft (21.3 m) from the Cenote Odyssey entrance. When they found his body, they took some photographs of it, documented the location where he was found, and left the body and his equipment intact. After this, they left the cave and returned to the surface to inform the surface support team and the authorities about their discovery.

Recovery Teams Formed

They couldn’t return to recover the body from the cave because it was still dark, so they planned to go for it the next morning. On April 24, 2022, early in the morning, the search and support teams met at the dive site to reassemble themselves into new groups to complete the recovery. One member of the recovery team was Alex Álvarez, who served as a surface support and point of contact with the authorities; other members who served as both search and recovery team members are Arthur Nguyen-Kim, Gustavo Buenrostro, Marissa Eckert,

Martin Gaspar Ramirez, and Kim Davidsson. They formed two recovery teams after planning how they would carry out the operation. Martin and Kim were on team 1, and Arthur, Gustavo, and Marissa made up the second team. Each of them went in with side-mount cylinders and a DPV to scooter to the dead diver and bring his four tanks and DPV back to the surface.

The recovery operation went very smoothly because they just had to go straight to the known location where the body was found the previous night. The body of the diver and the equipment he used was recovered and brought back to the surface. Marissa and Gustavo carried the body while Arthur took all the jumps he fixed for navigation, and they got to the surface successfully at around 1:30 p.m. the day after the accident.

The deceased diver’s gear that was recovered included a Blacktip brand DPV and four aluminum tanks that were each filled with 32% nitrox, as shown on the cylinders. His dive computer profile and survey data were used to track the places he went within the cave, and he made use of a MNemo survey device to collect his survey data.

They saw the diver’s body very close to the place where he had clipped his stage tanks to the line. His two side-mount tanks were still intact on his body, and the valves on both tanks were fully open, but both tanks were found empty. He was lying horizontally, and his head was facing the bottom of the cave. He had his helmet still on his head, and his mask was on his face without any traces of blood on it.

He didn’t look like someone who had any struggles before he died. But the positions of the valves in the two-stage tanks initiated a lot of questioning by fellow divers as to what caused the death of the diver. The two tanks were clipped off to the guideline according to standard principles for hoses, and his regulators were accurately fixed.

One of the stage tanks was empty with its valve strangely fully open while the valve of the second stage tank was closed, and the tank was pressurized with 170 bars/2500 psi of remaining gas. His DPV was also clipped to the line at the same place and was still in good working condition. A survey tablet was found in his pouch, along with a wrist tablet that has several sheets with some data already on them.

Possibly he was re-surveying the lines that were close to the location where he fixed the staging tanks and DPV. But there were no available details of his dive plan. When the divers tested every piece of their equipment, as witnessed by the police officers, they were all functioning properly. Three of his tanks were exhausted, but one was still containing 170 bar/2500 psi of gas when they found it. The result of the analysis ascertained that the remaining gas was 32% nitrox.

They also checked for any likely malfunctioning of this equipment by connecting all of his regulators to a full tank, but nothing was wrong with them. The regulators, o-rings, and hoses were fully functional. All of them were high-quality brands and were still looking very new and well-managed. Martin and Gustavo dived into the cave two more times just to examine and collect more data about the deceased diver’s route and navigation.

The second was that they followed the assumed path that he took according to the information gotten from his dive computer profile. During this last dive, they found his MNemo, which he had used for mapping and as a surveying device. Also, they were able to regenerate his dive profile, which looked so similar to the time, distance, and depth recovered from his dive computer.

Assumptions about the Diver’s Route and Navigation

They admitted that he had set up a “base camp” through which he would explore and also map the lines in that part of the cave. They concluded that he might have used his scooter while entering the cave and also made use of a stage tank, which he probably fixed off before starting to swim with the other stage bottle. He possibly left his DPV on site and returned to “base camp” when he was done mapping the adjoining lines.

He returned to “base camp” to drop his second-stage tank during one of those not-too-long dives. They believed that he might have reconsidered his remaining gas at this point and continued with his surveying activities since he wasn’t new to the environment he was in. When he moved a bit further, he put in the third jump and continued with his exploration.

He was still using his side-mount tanks intending to conclude the mapping of that section of the cave. Details from his dive profile show that he was trailing this jump line for about 10 minutes. Then he found a reassuring crevice that was leading to a deep, uncharted part of the cave. He decided to continue toward the end of the line he had been following.

He turned back towards “base camp,” using only his two side-mount tanks and the MNemo to finish the mapping of the cave line. At this time, his side-mount tanks would have been at turnaround reserve pressure. While returning to the entrance, he decided to look into the crevice he saw earlier. In this uncharted part of the cave, there was a very narrow vertical restriction that could only accommodate one diver at a time.

Because of this tight section, he found himself in, he couldn’t escape from silting out in the cave, which later resulted in zero visibility. Finding himself in total darkness meant that he would start panicking and searching for his way to the entrance without seeing what was before him.

These unexpected situations and the depth to which he was in the cave most likely made him use up one of his side-mount tanks. But he was able to get out of the hole he entered and quickly went back toward his stage tanks and DPV. While going, he put down his MNemo on the way, and it was later found just some distance away from the place where his body was.

Unfortunately, he couldn’t make it to his stage tanks before he got drowned just 1 ft (0.31m) away from those stage tanks and the DPV, which he would have used to get out of the cave. It was believed that improper gas management contributed to his death due to the assumption that he made a recalculation of his available gas at some point during his exploration. Recalculation and restarting make the reserve on board continue to reduce.

The reason why his stage tanks were fully drained even though they were properly fixed on the line wasn’t known. The victim was known to be a meticulous diver, so he wouldn’t have drained the tanks, knowing well that such action would spoil the cylinders. So they assumed that he used most of those tanks during his surveying activities, forgot to close the valve at the end of his work, or there was a free flow from the attached regulator that left the tank drained.

Several unanswered questions continued to be raised in the cave diving community as a result of the unknown cause of his death. So, all divers must be conscious of the fact that whenever they are entering a cave, they must be ready to accept whatever the risk associated with cave diving is. The body of the deceased diver was taken by local authorities for proper burial arrangements.

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