In deep snow with only a few supplies, the simplest and most efficient design is a snow cave or an A‑frame snow house. First find a slope where the wind blows downhill, dig a shallow pit, and pack the snow walls high. The entrance should be on the windward side so you’re protected from drafts. Use a tarp or old sleeping bag as a roof; lean it against the packed snow walls and secure it with a few branches or rocks. Line the inside with insulation – a thick sleeping pad or extra layers of clothing – to keep heat from escaping. Keep the opening small and close it at night with a snow door. It’s quick to build, uses the snow as natural insulation, and stays warm as long as you keep the interior dry. Just remember to stay away from the edges where the snow might collapse.