Bertie Gregory and other experts explain how to not get eaten by a shark

Yahoo

02-07-2025

Slashing teeth, lifeless eyes, and a taste for human flesh—that's what most movies might have us believe is typical shark behavior. But what is it really like to be in the water with these apex predators?
Sharks have been on Earth for longer than trees, and there are more than 500 species—from the infamous great white and iconic hammerhead to the gentle whale shark and pocket-sized dwarf lanternshark.
(This was the best place on Earth to see great white sharks—then they vanished.)
Regardless of size, sharks can be unpredictable, so it's important that those who share the water with them have knowledge of, experience, and respect for the animal.
So what does it take to swim with sharks? Ahead of National Geographic's Sharks Up Close With Bertie Gregory premiere on July 5, streaming on Disney+ and Hulu the next day, we talked to shark experts to find out how they prepare for these endeavors.
While filming the show, National Geographic Explorer Bertie Gregory experienced his 'all-time favorite' shark dive in the 'spooky' Cathedral underwater cave in South Africa's Aliwal Shoal reef.
(Cape Cod may have the highest density of great white sharks in the world.)
As many as 40 spotted ragged-tooth sharks 'were just swirling around in this cave,' he says. Growing to around 10 feet long, these seemingly menacing creatures have 'terrifying looking mouths with hundreds of needle-sharp teeth.'
But Gregory wasn't afraid. 'Fear comes from a lack of understanding,' he says. He knows that needle-like teeth are designed for grabbing rather than slicing, which means 'prey needs to be a size they can swallow. I'm too big to fit down their throat, so they can't chew me.'
Even great whites—probably the most feared fish on the planet—aren't mindless man eaters. 'We're not on their menu,' says Gregory. 'We're low in fat, and we taste funny.' Adult white sharks have evolved to eat seals and sea lions because of their energy-dense blubber, as opposed to us sinewy humans.
Although shark bites are incredibly rare—there were 47 unprovoked bites in 2024, according to the International Shark Attack File—the best way to prevent any incident is to understand the conditions and the animal's behavior.
Shark scientist Melissa Cristina Márquez, who didn't appear on the show but has been diving with sharks for over a decade, always carefully reviews environmental factors before getting in the water with any shark species, but especially large ones.
'I never enter the water if there's a strong scent trail from bait or carcasses, unless it's a controlled research setting,' she says. For an experienced professional like Márquez, safety protocols are a non-negotiable. This includes working with a highly trained crew, following clear procedures, and using a safety pole when needed to make sure there is always something between you and an overly curious shark.
Time of day is also important. Predatory sharks tend to hunt at dusk and dawn, so experienced professionals usually avoid these times, especially when the water is murky. 'If they're hunting in poor visibility water, they could mistake a human for a seal,' says Gregory.
By the time a large predatory shark has taken a test bite and realized the human isn't food, the victim likely has catastrophic injuries, he says. 'It's about not giving them the opportunity to make a mistake.'
Some factors, however, are impossible for researchers to know beforehand—like how the animal is feeling. 'Is it hungry? Is it full? Is it hunting? Is it happy? Is it healthy?' asks Lacey Williams, a shark behavioral ecologist who appeared on the show. 'We can't ask, unfortunately.'
Sharks give off signals if you know how to read their body language. Signs that a shark feels uncomfortable or agitated include jerky movements, raising its head, lowering its pectoral fins to point downwards, and arching its back.
If Márquez notices an exaggerated swishing tail, the animal making tighter circles, bumping objects around it, or several close passes, 'that's a signal that it is time to exit the water calmly and quickly,' she says.
When you're in the water with sharks, it's important to stay calm, move slowly, avoid sudden movements, and 'have a healthy respect for what that animal is capable of,' says Williams. Always 'have your head on a swivel,' she says. Don't turn your back to the shark and always maintain eye contact. As ambush predators, sharks are less likely to see you as potential prey if you keep your eyes on them at all times.
Although it's sensible to be cautious, a shark isn't going to try to chomp on any human it sees. Many species—including hammerheads, puffadder shysharks and thresher sharks—tend to be timid and avoid divers.
(This is how we can share our coasts with sharks.)
For predatory species like tiger, bull, and white sharks, going after a meal uses up valuable energy, so they need to know their efforts will be worth the reward—and that they won't get injured themselves.
Márquez says she stays vertical in the water to appear as large and off-putting as possible, joking that she's not sure 'how much that actually works in my favor at a meager 5 foot 1.'
Experts also consider how to prevent stressing out the sharks. 'These are wild animals, and every encounter should be on their terms,' Márquez says. That means giving them plenty of space and never chasing or cornering them. 'Swimming with sharks is a privilege, not a thrill-seeking stunt,' she adds.
Most importantly, never, ever try to touch a shark. 'None of us really like being touched without our consent,' adds Williams, so the same goes for sharks and other animals.
Some experts worry that the rise of social media footage of professionals interacting with sharks encourages people to take unnecessary risks—and sometimes get hurt. People 'think they can just go up and touch them or ride them, and that's very much not the case,' Williams says, even for docile species.
When it comes to sharks, people are usually concerned about the wrong thing, says Gregory. With these majestic animals threatened by human activities—including overfishing, habitat loss, and pollution—he says, 'we've spent far too long worrying about sharks when we should be worried for them.'