The PFD, or life jacket is your single most important piece of safety equipment. You need to choose one that fits well and you should wear it whenever you're on the water. This means wearing it securely and not just throwing it over shoulders, because it can actually impede your ability to swim if it's not worn correctly.
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Browse all Kayak Life Jackets in the gear guide or check out a few right here, just don't go paddling without one!
It should fit like a good pair of shoes, snug but comfortable. A good fit test that you can do before hitting the water is to tighten up the life jacket as you would wear it, then hook your thumbs under the shoulder straps and haul upward. The jacket should stay in place around your body and not ride up around your ears.
Any life jacket that's Coast Guard approved, fits well, and is comfortable enough so you don't feel the need to take it off when you're on the water, is a perfectly good life jacket. But the best life jackets for kayaking are those that are made specifically for paddling.
Kayaking specific PFDs have large armholes and keep the bulk of the flotation away from the shoulders and upper chest to give you the fullest range of arm and upper body motion while paddling. Many of them will also have convenient features like zipper pockets for carrying such things as sunscreen, glasses and snacks. And some models even have pouches for hydration bladders that can be mounted on the back of the PFD.