Leashes were introduced in 1971 by Pat O'Neill, son of Jack O'Neill (creator of the O'Neill Wetsuit). Pat gave out an earlier design of the surfboard leash to his fellow competitors at an international surfing competition. He was later disqualified for using the leash, but leashes became an acceptable and widely used device the following year.
What exactly is a surfboard leash?
A surfboard leash is a cord that attaches to your surfboard. It prevents the board from being swept away by waves and stops runaway boards from hitting surfing partners and nearby swimmers. Today's surfboard leashes feature a Velcro strap that attaches to your trailing foot while the opposite end attaches to the tail of your surfboard.
Why should I use a surfboard leash?
Before the invention of the leash, surfers who suffered a wipe-out had to swim to retrieve their boards again. Loose surfboards pose a danger to both swimmers and fellow surfers alike. Up to 66% of surfing related injuries are caused by collision with a surfboard. While surfing injuries are usually minor (from bruising to deep cuts), exposing open injuries to the ocean risks developing an infection.
Surfing also carries the danger of drowning. A surfboard acts as a flotation device when you're too tired to swim, but it can be easily separated from it's user and therefore unreliable. You can lower the risk of drowning by using a leash. You can further minimize the risk of drowning by always surfing with at least one other surfer.