The water in your bottle might turn into ice by morning, and while that would be very entertaining to watch, you'd rather get a good night's rest in the Marmot Ultra Elite 20 Sleeping Bag. This ultralight bag uses Marmot's latest innovative insulation ElixR Micro, which uses three different fibers that maximize warmth and compression like a down bag, but since it's a synthetic it can withstand moisture-riddled environments better than feathers ever could. Despite being a synthetic bag, the Ultra Elite was able to manage staying under two pounds to keep the weight off your back during the approach.