By Issy Ronald, CNN
(CNN) — The light fades as divers disappear farther into a cave system, until the greenish hue from their flashlight is all that’s visible, bouncing off walls, picking out creatures humans might never have seen before, and illuminating a world otherwise confined to total darkness.
These caverns can extend for hundreds of miles, dangerous, otherworldly mazes unlike anywhere else on Earth.
Any cave diver is well aware of the dangers involved in exploring these alien zones. In a 2024 documentary, “Diving Into the Darkness,” veteran Canadian cave diver Jill Heinerth recalls swimming “through the graves of my friends all the time. That list is well over a hundred people.”
The dangers of this highly specialized discipline were underscored once again this month when five Italian divers died while exploring the Vaavu Atoll caves in the Maldives on May 14, and Maldivian military diver Sgt. Mohamed Mahudhee also died attempting to recover their bodies.
Diving instructor Gianluca Benedetti’s body was found at the mouth of the cave, and the other four divers — Monica Montefalcone, an associate professor of ecology at the University of Genoa; her daughter, Giorgia Sommacal; Federico Gualtieri, a marine biologist; and Muriel Oddenino, a researcher — were all found in the deepest part of the cave system.
But even though they are acutely aware of the dangers, something constantly draws back cave divers who dedicate, and sometimes sacrifice, their lives to exploring these strange underwater worlds.
Navigating only with flashlights and a guideline — the thin thread that allows divers to find their way back to the cave entrance — they glimpse another side to life on Earth.
Cave divers often describe their chosen habitat as space-like, a whole other world filled with stalagmites, stalactites and alien-like creatures. Diving in these underwater cave systems is like “swimming through the veins of Mother Earth,” said Heinerth, who has completed more than 8,000 dives.
“Astronauts have that overview effect where they talk about looking back on the great blue planet, and they can never look at Earth the same way again,” she told CNN on Tuesday. “I guess I’m having a similar effect from being inside the planet … I’m literally within the sustenance of the planet that’s supplying the water for humanity, wildlife and even all of the industries we require for our modern life.”
‘All the things that could go wrong’
So many things can go wrong during a cave dive. Equipment can fail; guidelines can break; visibility can become nigh on impossible. And, if things go wrong, you cannot just ascend to the surface as in other types of scuba diving. You are reliant on your own wits, and your dive buddy.
While exploring these systems, cave divers will routinely squeeze through incredibly tight spaces. Sometimes, “my shoulders are scraping the ceiling and my belly is on the floor, and I can see less than a meter in high flow as the sand and silt is blasting me in the face,” Heinerth said.
So, before any dive, before she does anything else, Heinerth will “rehearse all of those things that could go wrong, all of the things that could kill me in this environment.”