These Are the World’s Most Terrifying Scuba Dives

Like many people, we love challenging ourselves to touch the bottom of whatever pool we’re swimming in, but we’d advise against doing this at Deep Dive Dubai, the world’s deepest pool. With a depth of 60 meters (roughly 197 feet), it’s used as a training ground for some of the world’s top freedivers, and although only a handful of people will ever reach the bottom (which is double the maximum depth advanced open water divers can dive to), there’s plenty for snorkellers and divers with basic PADI qualifications. The pool, which has dry rooms filled with spare oxygen tanks and two-way radios at various depths, is filled with props designed with selfies in mind, and some of the best ones (including a submerged sports car, snooker table, and bicycle) are just a few meters below the surface.

A chain of islands and a notorious shipwreck spot, one of the Abrolhos archipelago’s biggest magnets for divers is the wreck of the Batavia, which sank in 1629 after it crashed into a reef and broke apart. Strong swells (the same ones which undoubtedly led to the ship’s sinking) are one reason divers should ideally have either a shipwreck or advanced diver qualification—not just to explore the shipwreck, but the area in general.

“One thing which makes this area special is the Leeuwin current, which swirls its way past the Abrolhos,” says Jay Cox, owner, and operator at Eco Abrolhos. “It brings crucial nutrients from the northern hemisphere, and the fact that this is where tropical waters from the north meet the temperate waters of the south means there are many endemic species of corals, seaweeds, and fish.”

One of Australia’s most spectacular dive sites, the SS Yongala, was a ship that set sail from Sydney in 1911. It was due to arrive in Townsville in Far North Queensland a few days later. Sadly, nature had other plans—namely, a cyclone that thrashed its way along the coastline. The ship sank shortly before it was due to arrive in Townsville, and all of the passengers perished. Strong currents and its remote location mean that divers need an Open Water Advanced certification and 15 logged dives, but we guarantee it’s worth the effort. The visibility is fantastic, and the SS Yongala’s masts and bow are clearly visible–you’ll even be able to make out the ship’s toilets (trust us, that cramped toilet on your dive boat will look truly palatial compared to these).

If you’re prone to claustrophobia, the thought of diving into this next site might send shivers down your spine. That said, a certain amount of shivering comes as standard at this spot, where divers plunge into an alpine lake and swim beneath the ice. You’ll be tethered to a rope and will wear a neoprene dry suit (trust us, this isn’t somewhere you want your gear to spring a leak), and although there aren’t corals or tropical fish, the beauty is the silence and changing appearance of the ice.

“The colors vary depending on the ice thickness and whether it’s sunny or cloudy,” says Dan Arbaogast from ice diving operator 50shadesofblue.fr. “You’ll see blues, greens, yellows, and sometimes some reds. It’s like entering a church—it’s surprisingly bright, but there’s total silence. There’s not much aquatic life at 2,000m above sea level–instead, it’s about the beauty of the ice and the bubbles.”

Almost everyone who’s visited Iceland has seen a volcano or watched a geyser erupt, but how many people have swum between two tectonic plates? The Silfra fissure formed when the North American and Eurasian plates collided. Subsequent earthquakes opened up an underground spring that filled the fissure with glacial water, and it’s now a popular snorkeling and diving spot.

This glacial water is said to be the clearest in the world, which is a good thing because divers need to keep their wits about them here. Frequent earthquakes mean new caves are constantly opening up, and loosened boulders regularly tumble into the fissure.

“Diving the Silfra dive site is a unique experience,” says Dive Worldwide’s Sarah Wight. “Divers can immerse themselves in crystal clear cold water between two tectonic plates which continue to move apart. It’s an evolving and natural site, and definitely one for the logbook.”

If you vowed never to swim in the sea again after watching the film Jaws, this next site might not be for you. Osprey Reef, in Australia’s Tropical North Queensland, is one of Australia’s most technically challenging dive sites, as well as one of the best places to swim with sharks (reef sharks and white-tip sharks are the species you’re most likely to spot).

Other features include the Fairy Grotto, best described as a coral mountain riddled with tunnels that divers can swim through, and the Admiralty dive site, where obstacles include an enormous anchor lodged in the center of an underwater tunnel. Fancy cranking up the fear factor? Sign up for one of the popular night dives, and you’ll explore the reef at night, armed with only an underwater torch.

There’s a reason Egypt’s Blue Hole dive site is known as the Diver’s Cemetery. It’s one of the world’s most popular freediving destinations, and countless records have been set here, including many set by freedivers who (on a single breath) dive down to an underwater archway located at 56 meters below sea level before swimming through it and returning to the surface.

It’s a popular scuba diving spot, albeit an incredibly challenging one. Divers enter the Blue Hole through The Bells, an underwater passage that earned its name because of the sound made by divers’ tanks when they scrape along the walls. Tragically, countless divers have died here, a reminder of which is the collection of plaques nailed to nearby rocks.

The Samaesan Hole, just off Samaesan Bay, is the Gulf of Thailand’s deepest dive site, with a depth of 85 meters. Divers must possess advanced diving qualifications and carry additional kits, including torches–the site’s depth and complex layout mean there are many spots that sunlight can’t reach. But there are other reasons it’s considered one of the world’s most dangerous dive sites. These include strong currents, the large number of trawlers and gas tanks that pass through the area, and unexploded bombs. Yes, you did read that correctly. In the past, the site was used by the military as a dumping ground for unexploded bombs, many of which can still be seen on the seabed.

Mount Gambier in southern Australia is a magnet for sinkhole and cave divers, who come to explore locations such as the Engelbrecht Caves, an experts-only dive site comprising a series of limestone caverns, some of which are located directly under the city of Mount Gambier. The huge network of narrow tunnels makes this one of the more challenging dive sites, although the nearby Shaft is the one with the highest fear factor. Divers enter this underwater cave via a narrow shaft, the size of which means their kit must be lowered separately (a winch is used to lower both divers and kit into the depths). Once inside the soccer field-sized main cavern, divers can explore a network of tunnels and overhangs, albeit in almost total darkness.