A properly fitted personal flotation device (PFD), of course, is a must. Life vests for
kayaking are specially designed to integrate with a spray skirt and to fully allow for the paddler's comfort and range of movement in the cockpit.
In a waterproof bag or container, store your first-aid kit with the essential on-the-go salves and treatments for blisters, fishhook-punctures, sunburns, cuts, and other minor injuries. Assess your first-aid kit regularly to make sure it's well-stocked, and replenish any supplies that have been depleted.
Out on the water, it's important to be able to make yourself seen--whether it's to ward away larger boats to avoid a collision, or it's to advertise an emergency situation to potential rescuers. Along with a whistle, suitable tools for this purpose include flares, airhorns, and signaling mirrors. Remember that three blasts of sound or light are the international signal of distress.
The old phrase "up a creek without a paddle" should remind us that a paddle is a kayaker's best friend, and that a kayak without one is no longer under your control. That means you need to be prepared in case your paddle gets away from you: A paddle leash helps you retrieve a wayward one, but remember to pack a spare on any trip as well.
You've got your life vest--good--but you also want to carry floats in the event your boat capsizes or you're swept overboard. Carry flotation bags to keep a swamped kayak buoyant as well as a paddle float to help you get back into the cockpit. A towline allows you to secure and transport a capsized boat or friend. Pack a pump so you can bail out water from the kayak if necessary.
For a whitewater kayaker, exposed as he is to the huge boulders and chaotic debris jams of a fast-moving river, a helmet is as essential as any other piece of safety gear.
Every kayaker should carry a compass and appropriate map, even on short outings. It goes without saying that said kayaker should also know how to use those most vital and failsafe of navigational tools; practice on familiar waters in non-emergency situations.
Other fundamental safety items to securely pack in your kayak include a repair kit, fire-starting materials, and a knife. Falling within the realm of self-protection as well are adequate water, sun protection, and extra food.