Cold-water diving, not to be confused with ice diving, often involves diving in near-freezing water temperatures. For example, Silfra Fissure, a popular dive site between two continental plates in Iceland, sees water temperatures colder than 40 degrees F (1-2 C) year-round. So what, then, is the difference between cold-water diving and ice diving? Ice diving refers to diving beneath a solid or broken layer of ice that exists over a portion or the entirety of the dive site. Simplified, ice diving always involves an overhead environment and cold-water diving does not.

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In order to dive safely under the ice, divers take additional precautions unique to ice diving:

• The diver is always tethered to a safety line, which a dive buddy team at the surface holds. The diver wears a specialized harness, clipped to the line so that equipment doesn’t interfere with the tether. The safety line is used not only for emergencies, but also as a communication device while under the ice.

• Each dive buddy team is increased from two to four members. Only one of the four members dives at a time; the other three play different surface support roles throughout the dive, ensuring the submerged diver’s safety.

• Dive times while using recreational scuba equipment are typically limited to less than 30 minutes. This time limit reduces exposure to freezing temperatures and provides plenty of extra air in case of an emergency. 

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Why learn to dive under ice? The chance to see penguins and leopard seals underwater comes to mind, but the Arctic isn’t the only place for ice diving. Much of the Northern, and some of the Southern, Hemisphere experiences below-freezing temperatures each year, so marine and freshwater bodies could be partially or completely covered in ice and snow. When you can’t afford to travel to the tropics, why not enjoy winter diving in your own backyard?

Beside the beauty of the surface ice layer, ice diving provides unique animal experiences and dive activities that you won’t find anywhere else. Under wintertime conditions, cold-blooded aquatic animals slow their metabolisms dramatically, meaning they don’t move if they don’t have to. As long as a diver swims calmly, he or she can approach fish and invertebrates within unusually short distances. Fill up your drysuit and invert your positioning, and you can even observe those animals while standing upside-down on the surface ice.

The cold water inherent in ice diving has benefits as well. Clarity in freshwater bodies tends to increase dramatically in the winter. The lack of water circulation allows particulate matter to settle. Animals and objects you may never see in summertime are easily visible under ice. Learn to deal with near-freezing temperatures and you’ll have some of the clearest dives of your diving career.