No sport demands a greater awareness of timing than scuba, and ice diving only intensifies the life-and-death nature of this limitation. Not only are you unable to surface wherever you like thanks to a frozen layer – potentially trapping you in polar waters – but also consider that each minute in this extreme environment increases the possibility of bodily harm due to nerve damage and hypothermia. But brave it all, and you'll witness the striking beauty of icebergs and a world where visibility can stretch 60 meters.
Beneath the ice in a bikini
Where: Lake Päijänne, Finland
Why: Thrill seeking
Danger factor: 8
Doctors warned French freediver Chloé Villaume that she'd have just three minutes to swim in 2°C water wearing only a bikini before nerve damage to extremities could set in. Stig Severinsen, famous for below-the-ice plunges, also warned her of fainting.
"There was a risk, but I didn't really think about it," she says. A lanyard connected her to a team of five safety divers on the surface and in an emergency, they would fish her out in 10 seconds. For Villaume, the swim proved only refreshing. "It gave me adrenaline – I felt really good afterward."
Cut a hole in Canadian ice
Where: Morrison's Quarry, Wakefield, Quebec, Canada
Why: Sharpen ice-diving skills, and admire designs that fellow divers create on the surface by shoveling snow off the ice
Danger factor: 4
Training to ice dive builds procedural muscle memory, but first it shifts perception. "I was afraid it was going to be dark and claustrophobic under the ice," says underwater photographer Jo-Ann Wilkins. "Instead, it's luminous."
Once you adjust to the environment, you work on acclimating to the system of ropes linking you to your dive buddy, and to the surface.
"Someone at the surface tugs the rope to ask you if you're OK, and you tug back to say yes," she says. The biggest emergency is when a diver fails to return a tug says Wilkins, "That's why there's always a safety diver fully dressed at the surface, ready to jump in and find the missing diver."
See ships under the ice
Where: Fathom Five National Marine Park, Tobermory, Ontario, Canada
Why: Explore wrecks, such as the John & Alex fishing tug
Danger factor: 8
With broken ice, your biggest support is the Weather Channel – the best way to prepare is to study the wind conditions. "Fifteen knots is way too much," says underwater photographer Jerzy Kowalczuk. Strong winds will send ice formations piling-up in one direction. "Then you find yourself without an exit point. When that happens, keep swimming, pushing ice out of your way," says Kowalczuk. "Sometimes people think diving under broken ice is easier, but it's not – it's much more dangerous."
Meet a beluga whale
Where: White Sea, Russia
Why: Face-to-face encounters with beluga whales
Danger factor: 5
The ice sheeting Russia's White Sea can thicken to five feet in places, but near the town of Kandalaksha it never freezes over: To breathe, a pod of beluga whales continuously nudges at the surface, keeping it from hardening. Here, the risk isn't in the water - it's getting there. The most dangerous part is the one kilometre snowmobile ride to the put-in.
"It's not comfortable because when the ice starts breaking, you have to keep hopping out of the sled," says underwater photographer Franco Banfi. "The bigger problem is that the snow will cover the cuts in the ice," he says, which is why he only travels to the site with experienced local drivers. Says Banfi, "If you go by yourself and ride over those cuts, you could fall in."
Under icebergs in Greenland
Where: The fjord of Tasiilaq, Greenland
Why: Galleries of iceberg art
Danger factor: 9
"Nobody has dived here before – there are no dive maps," says underwater photographer Tobias Friedrich of Greenland, home to some of the world's largest and most dangerous icebergs.
The biggest danger is a collapsing iceberg. "We only dive the smaller icebergs – the big ones are too dangerous," he says. With each one, Friedrich visually scans for overhangs, bridges and cracks.
"If a big iceberg breaks apart, one piece can overturn the boat," he says.
But the constant cracking and breaking of the formations is also what makes them beautiful. "You can dive one iceberg, and you may want to see the same one the next day, but it will have flipped to become completely new – it's magic."
Traverse an underwater ice tunnel
Where: Lake Sassolo, Switzerland
Why: Explore underwater tunnels
Danger factor: 8
"Ice like this can collapse anytime," says underwater shooter Franco Banfi of the freshwater icebergs in this lake near his home. Melt and run-off carve tunnels in the pristine packed snow, but also cause breakage – hastened by diver exhalations.
Because of this, Banfi's model was hesitant to pose. A collapse can happen in 30 seconds, burying a diver in a snow-and-ice avalanche.
"You can usually hear the crack, but not always," says Banfi. "And if you hear this, it's already too late."