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This story originally featured on Field & Stream.

When you are hunting or camping in cold climate, one piece of gear that you really, really don’t want to get wet is your sleeping bag. If you’ve ever had to dry your bag around a backcountry fire for hours on end, then you know what I’m talking about. But if you’re backpacking in the mountains, all it takes to soak your sleeping bag is a full day of rain (or a misstep when you’re fording a creek). And if that happens, the threat of hypothermia becomes very real. So, before you head into the backcountry, it’s essential to take the time to waterproof your bag. Here are the steps you’ll want to follow to ensure that you have a warm, dry bag—and a comfortable night’s sleep.

Start by waterproofing your compression sack

Stuff your sleeping bag into a dry compression sack that you lined with a plastic trash bag. Dry compression sacks have waterproofing on the inside of them, but repetitive stuffing and unpacking will eventually destroy that waterproofing. The trash bag lessens the abrasion on the dry compression sack and extends its life. It also acts as a secondary line of defense if your dry compression sack does leak after extended submersion. As you stuff the bag into the sack, use your body weight to get the bag as compact as possible and to push out any air in the sack. Once it’s all nice and snug, tightly roll the top of the compression sack and clip it shut. Lastly, cinch the compression straps along the sides of the dry sack, little by little and rotating as you go, to get an even compression.

At this point, as long as you’re certain that your dry compression sack doesn’t have any leaks, you’re good to go. However, if you’re gearing up for a river trip where you might encounter whitewater, you’ll want to take some extra measures.

At this point, as long as you’re certain that your dry compression sack doesn’t have any leaks, you’re good to go. However, if you’re gearing up for a river trip where you might encounter whitewater, you’ll want to take some extra measures.

Gear tips for maintaining a dry and warm sleeping bag

Down vs. synthetic: how to find the right sleeping bag

If your sleeping bag does get wet, a synthetic bag will dry more easily and will hold heat better than a down bag. You are best off with a four-season synthetic as a go-to bag; just leave it unzipped in warmer weather. A three- or two-season bag will lighten your load, but you’ll want to carry a compact, insulated liner for when the temperature drops (more on liners below). Your other option is a down sleeping bag. Down is warmer, and lasts longer, than synthetic. The only issue is that when down gets wet, it is pretty much useless. But if you follow the tips outlined above, you should be fine with a down bag.

Your sleeping bag should be water repellant—not waterproof

A breathable water repellant spray, such as Nickwax TX Direct Spray, will help keep the moisture out, particularly at the foot of your bag where condensation tends builds up. But don’t use a heavy, non-breathable treatment: You’re looking for water repellency, not waterproofing. Otherwise, your bag won’t be able to “breathe” and let moisture from your body escape, which can cause the bag to get damp and cold. For the same reason, you should avoid buying sleeping bags that come with a built-in Gore-Tex outer layer.

Why you need a sleeping-bag liner

Here’s why: Because sleeping bags don’t only get wet from the outside in. A sleeping-bag liner is particularly useful in the fall and winter, as it can substantially add to your bag’s R-value without increasing the weight by much. A liner will also prevent your body’s moisture from building up inside your bag.

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