Tree wells in deep snow: hazard, not shelter

The dense lower branches of conifers catch falling snow. Beneath them, at the trunk, less snow arrives and it is hardly compressed. All around, by contrast, the snow lies deep and becomes firmer under its own weight and through wind. So a hidden hollow of loose snow forms next to the trunk.

If someone falls in, especially head first, loose snow slides in from the edges and from the branches. Arms and legs find no grip because there is only powder around them. The more you struggle, the more snow falls in and the deeper you can sink. Snow in front of the mouth and nose can very quickly make breathing very hard.

What makes it especially treacherous is that you cannot see the danger: the well can be hidden by branches and a thin layer of snow.

With plenty of fresh snow and dense conifers, expect tree wells even if you see no hollow. In deep snow keep as wide a distance from trunks as possible, especially when descending on skis or a snowboard and when walking downhill on snowshoes.

Never travel alone in snowy forest. Stay close enough to your companions that you can see and hear each other, and wait for each other regularly. A person who disappears is only found if someone notices where they were last.

Snow on the branches is also a hazard: it can fall and bury a well or a shelter beneath it. For an emergency bivouac, therefore, choose a sheltered spot next to the tree, not in the well, and look up to see how much snow lies on the branches.

If you fall in yourself: if possible, hold on to branches or the trunk. Use your hands to create an air space in front of your face. Stay as calm as you can, because violent struggling makes you sink deeper. Call or whistle for help – a whistle on your pack strap is ideal for this.

If someone in your group has disappeared: one person calls the local emergency number (112 in the EU) at once while the others search at the same time. Clearing the airway takes priority. Dig with a shovel from the side towards the head rather than stepping into the well from above – otherwise you press even more snow onto the person.

These points are only basic principles. How to care further for a buried person is something you learn in a first-aid course; follow the instructions of the emergency dispatcher.

Older military survival manuals such as FM 3-05.70 describe the tree pit as a possible snow shelter. Ski areas and mountain safety organisations, on the other hand, warn of suffocation accidents in tree wells in deep snow. Both can be reconciled: a shallow, firmly packed hollow can offer shelter; a deep funnel of loose powder is a trap.

This entry is therefore deliberately written as a warning, not as building instructions. Anyone travelling in deep snow gains more safety from keeping clear of trees, partners in sight and a whistle than from any shelter at the trunk.