A deep snow or tree well immersion accident occurs when a person falls into an area of deep unconsolidated snow and becomes immobilized and suffocates. Deaths resulting from these kinds of accidents are referred to as Snow Immersion Suffocations (SIS). Most tree well incidents have occurred at ski resorts in the Western United States and Canada, although the same risk is present wherever deep powder conditions are found.

As a climber, you are less likely than a skier/boarder to fall into a tree well inverted but it can still be done. You may drop into a well if you stray too close to a tree on a glissade or you may simply step or back into a well while you are distracted or are seeking shade or shelter from the elements. If you are skiing or snow boarding, your risk for tree well immersion and SIS is higher. Most tree well immersion accidents are completely avoidable. Avoid trees and the well around them as you are climbing and descending and use your hiking/skiing poles to probe for snow depth and stability if you are seeking shade or shelter near trees.

Most victims of tree wells land upside down in the hollow. If you do find yourself in a tree well or other awkward position in deep snow, try the following:

• If you feel yourself sliding into a well, try to stop the movement. Grab onto branches or throw yourself to the ground spreading out your weight.
• If you can’t stop your slide, do everything you can to make sure you don’t go head-first into the hole.
• Don’t panic after you have fallen in. Any movement will just encourage more snow to fall on you, restricting your breathing.
• Grab onto the tree trunk or branches. By doing so, you should not fall farther into the hole.
• If you can, carefully move your head to any available pockets of air or clear a small space around your mouth.
• Shout for help. Hopefully your climbing partner will hear you and come to help you out of the hole.
• If you’re alone, don’t panic. You can still get out of this situation.
• Try to turn around or pull yourself up using the tree as leverage. This will be difficult but take your time and persevere.
• Once upright, spread your weight across the snow and push yourself clear.

Numerous websites provide information about how to avoid falls into tree wells and what to do if you fall into one. Here are a few. Check them out!

• Tree Well and Snow Immersion Suffocation Information Site
• National Ski Areas Association

A tree well demo video shows you how much of a hazard tree wells can be.

If you want to see a tree well immersion and successful amateur SIS rescue, check out this heart-pounding video. Note: This rescue has mistakes and is not a representation of proper technique. The intent of this video is to demonstrate and educate people on the dangers of tree wells. It is NOT a demonstration on HOW to rescue someone from a tree well.