[leadin]Tree wells form close to the trunks of trees in deep snow. The snow near the tree’s trunk and branches becomes very soft and sugary over the course of a winter, and can trap a skier or snowboarder so badly that they can die from suffocation. This video shows a man’s son going headfirst into a tree well, and the resulting panic.
This is why you always ride with a partner, and keep an eye on each other, when riding near trees.[/leadin]