Get comfy in a cozy snow cave this winter

By Stephen Hlawaty
Outdoors Columnist

Spending a night in a snow shelter is one of the most adventurous things many of us can do. If done incorrectly, however, the night could be our last.

Snow shelters lie in the balance between life and death. Perhaps no other people understand this as well as the Inuit tribes of the Arctic regions. Inhabiting an area that extends from the Aleutian Islands, across Arctic Canada and into Greenland, the Inuit have managed to survive in one of the world's harshest environments for millennia by sheltering themselves in little more than snow and ice.

Among the many types of snow shelters used throughout the world, the most common is the snow cave. Snow caves have provided both emergency and recreational winter shelter for many outdoor enthusiasts. When properly constructed, the inside of a snow cave will remain a comfortable 32 degrees Fahrenheit. A single lit candle can increase the temperature by as much as 20 degrees or more. Following are the four main steps to building a proper snow cave.

Selecting a site

Select a site with at least 4 to 5 feet of snow depth. Selecting a site on the leeward side of a hill is best because this provides a natural deposition zone for wind-driven snow, so you'll have more snow with which to work. Be sure to stay clear of any avalanche danger and avoid building near tree wells. Tramp an area equivalent to the size of the cave you want to build. If there isn't 4 to 5 feet of snow underfoot, shovel snow until you form a mound at least that deep and as big as required. Once you've tramped down the area or built your mound, be sure to leave the area undisturbed for at least an hour before digging. This will allow the snow crystals to bind together and provide added strength and stability. Binding time will vary depending upon the snow type, its moisture content and the outside temperature. If you do not allow time for the snow to bind, it's possible for your cave to collapse in on you, as it did when my friend and I were building ours.

Tunneling in

After the snow has had time to bind, dig a trench alongside your mound, as deep as you are tall, downward into the snow. Any dug up snow should be thrown on top of the cave's roof area. Serving as an additional layer of protection, the trench can be lined and covered with tarps or tree branches. Once the exterior is complete, dig an entrance and tunnel at knee-height into the side of the trench and the mound of snow. The tunnel should be the length of your body and have a slight upward angle to it. This will prevent warm air from escaping once the snow cave is built. At the upward end of the tunnel, dig out a flat space to accommodate all who will be spending the night.

Shaping the interior

Try to shape the inside of your cave as a dome. This will provide added stability and insulation. Likewise, the walls of your cave should be at least 12 inches thick. The smoother your walls are, the less likely your cave will drip as the temperature rises inside. Build the cave large enough so that you can sit upright inside it.

Finishing the details

Bore a ventilation hole into the top of your snow cave. This can be accomplished with a ski pole, stick or similar object. The hole should be at least 2 inches in diameter. A ventilation hole allows for the release of lethal levels of carbon dioxide and monoxide that build up from normal breathing and burning of candles and cook stoves. Without some form of ventilation, these gasses can accumulate and asphyxiate all inside. Another helpful addition to your cave's interior is an elevated sleeping platform. This brings you closer to where the warmer air is. Lastly, you can carve shelves into the sides of your cave to hold candles and other items.

Once your snow cave has been built, roll out your ground cloth, air mattress and winter sleeping bag. Be sure to change into warm and dry clothes before bedding down for the night. Otherwise, chill out.

For more information, look to Ernest Wilkinson's book "Snow Caves: For Fun & Survival" (Johnson Books, 1992) or the video "Snow Caves: How to Keep Warm with Ice" with Bill Blumberg (Vernal Productions, 1996).