A snow cave is a shelter made in snow by mountain climbers and other outdoor winter recreational enthusiasts. The shelter has properties associated to an Igloo and is mainly effective at providing protection from wind as well as low temperatures. A properly made snow cave can be 0 °C (32 °F) or warmer inside, even when outside temperatures are -40 °C (-40 °F). 
A snow cave is built by excavating snow in such a way that the entrance tunnel enters from under the main space to retain warm air. Construction is simplified by building it on a steep slope and digging slightly upwards and horizontally into the slope. The roof is domed to prevent dripping on the occupants. sufficient snow depth, free of rocks and ice, is needed. Generally at 4 or 5 feet is enough. The snow must be consolidated, so it retains its structure. The walls and roof be supposed to be at least 12 inches thick.
A narrow entrance tunnel, a little wider than a human leads into the main chamber which consists of a flat area, perhaps with elevated sleeping platform(s), also excavated from snow. Most sources agree that using tools such as a shovel and ice axe are vital; digging by hand is for emergencies only.