Predicament: You're hiking alone and crossing a knee-high stream on a cold, rainy day when you slip on a mossy rock and fall backward into the icy water. You reach the opposite bank–but you, your clothes, and your pack are totally soaked.
Lifeline: Your biggest worry is hypothermia, which can kill in temps as high as 50°F when you're wet. Strip down, wring out clothes, then put them back on (if you don't have dry ones). "The water in dripping wet clothing will suck the heat out of your body much more than damp clothing," says Gordon Giesbrecht, PhD and the co-author of Hypothermia, Frostbite, and Other Cold Injuries. Wring out the rest of your clothes and layer them on, saving waterproof gear for the outer layer to protect from wind and rain.
Make a fire, if possible. If not, pitch your tent and take shelter. Get on top of a sleeping pad to insulate from the cold ground. If your sleeping bag is synthetic, wring it out completely and get in (a wet down bag loses its ability to insulate). Maintain body heat with food and exercise until the weather improves enough to walk out. Snack on foods with sugar, fat, and protein (like gorp with chocolate), sip a hot drink, and do sit-ups or push-ups in your bag.