If you are surfer you have probably heard of surfers' ear, also known as bony exostoses. It happens due to cold water entering the ear during sports such as swimming in the sea, surfing, kayaking and windsurfing. You are at higher risk if these activities are performed on a regular basis.
Bony outgrowths (exostoses) form in the ear canal as the body attempts to block the cold water entering the ear. Water can become trapped behind the outgrowths making ear infection much more likely. Eventually the bone meets in the middle and the sufferer goes deaf. It can be treated by drilling the bone out but prevention is better than cure. A decent pair of surfing earplugs for surfers' ear can help to keep water out of the ears and prevent surfers' ear form occurring.
Surfers' earplugs for surfers' ear need to be waterproof and well fitting. If they are connected by a cord you are less likely to lose them as you can tie them to the zipper on your wetsuit. Some ear plugs for surfing have an antibacterial in them which might help reduce the chance of ear infection. Make sure you read some reviews to make sure you get some decent ones.