Entering an ice tunnel
From BearWiki
Claim: Ice caves are dangerous places to be and make poor shelter.
As is near universal advice, taking unnecessary risks when your life isn't in immediate danger is a dumb thing to do. When lost, your chance of survival and rescue are extremely high and your chance of death quite low. Doing stupid things that can get you injured, however, flips the equation.
Entering an ice cave or tunnel is entering something that is by its very nature unstable. All ice caves and tunnels are transitive; some systems change slowly, but in other places, entire caves can form and disappear in less than a year. While there are risks of cave-in associated with normal caves, these pale in comparison to the risk from ice caves in some places, especially during summer[1][2][3]. Glaciers may groan, creak, and pop on the inside; you never can tell when one of the pops is a warning that tons of ice are about to fall on you.[4]
Why would you want to enter an ice cave (apart from the natural beauty)? Rarely is passing through an ice cave the shortest way to a destination, and even if it was, why risk it? As far as shelter goes, some are scoured out by wind or at least form channels for wind to follow, so putting yourself in the path of a wind scour isn't exactly finding shelter. Some are formed from meltwater, while others are scoured out by geothermally heated water. These are often the most dangerous kind, as the steam makes the ice even less stable than usual.
A safer route, if you must shelter out on a glacier, is to dig an ice shelter. Better, however, is to reduce the amount of ice that your body is exchanging infrared with and the amount that could collapse on you. If you have access to natural materials, covering a depression with branches or snow (if too few branches are available for insulation) makes a much better shelter.[5] You use whatever you have to survive.
