Environmental anthropologist Kenny Broad and one of his fellow researchers-cum-explorers know this for a fact after experiencing an "underwater avalanche" -- which is when sediment from the walls of the cave collapses in around the divers.
This, for reference, is how small a space they were moving through:
And below is what it looked like when the avalanche surrounded them.
"All of a sudden, it just started raining down on top of me," Broad explains in the video, noting that either the divers' fin kicks or pressure waves from their movements probably caused the sediment to come loose.
Broad and his team have been studying these complex underwater caves since 2008 as part of NatGeo's Blue Holes Project.
Advertisement
The caves, which serve as aquifers and collect the rainwater that filters through the limestone above, are "among the least studied and most threatened habitats on Earth," according to NatGeo. They hold a wealth of valuable scientific information, including unique biological, geological and cultural characteristics.
But studying them involves navigating the treacherous and claustrophobic territory, and then taking samples and snapping photos, all of which takes time -- a limited commodity when you're underwater.
And there's always the risk of unexpected complications, including underwater avalanches, which can result in little to no visibility.
As a precaution, the team always runs a guideline (think Theseus and the Minotaur) that leads back to the mouth of the cave -- a "golden rule" of cave diving.
"You have to assume that you're gonna come out in no visibility," Broad says in the video. "Without that line, you have low odds of getting out."
Advertisement
In this instance, Broad was able to find the line quickly, connect with his dive partner and swim out of the narrow passageway. In wider caves, however, finding the guideline can take much longer.
"It's only when you get to the surface and you see all your dive buddies next to you, you realize just how intense an experience you just went through," he said.
Also on HuffPost:
Incredible Underwater Photos
Support HuffPost
Our 2024 Coverage Needs You
Your Loyalty Means The World To Us
At HuffPost, we believe that everyone needs high-quality journalism, but we understand that not everyone can afford to pay for expensive news subscriptions. That is why we are committed to providing deeply reported, carefully fact-checked news that is freely accessible to everyone.
Whether you come to HuffPost for updates on the 2024 presidential race, hard-hitting investigations into critical issues facing our country today, or trending stories that make you laugh, we appreciate you. The truth is, news costs money to produce, and we are proud that we have never put our stories behind an expensive paywall.
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. Would you consider becoming a regular HuffPost contributor?
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. If circumstances have changed since you last contributed, we hope you’ll consider contributing to HuffPost once more.