Drowning

Drowning
Surfing, like all water sports, carries the inherent danger of drowning. (Anyone at any age can learn to surf, but must have at least intermediate swimming skills.) Although the board assists a surfer in staying buoyant, it cannot be relied on for floation if it becomes separated from the user. The leash, which is attached at the ankle, keeps the surfer connected to the board for convenience but does not prevent drowning. Surfers should be careful to remain in smaller surf until they've acquired the advanced skills necessary to handle bigger waves and challenging conditions.
           Top surfers have drowned in extremely challenging conditions. Some drownings occurred as a result of leashes tangling with reefs, holding the surfer underwater. In very large waves such as Waimea or Mavericks, a leash may be undesirable, because the water can drag the board for long distances, holding the surfer underneath the wave.

Collisions

Under the wrong set of conditions, anything that a surfer's body can come in contact with is potentially a danger, including sand bars, rocks, reefs, surfboards, and other surfers.Collisions with these objects can sometimes cause injuries such as cuts and scrapes and in rare instances, death.

Surfers often jump off jetties, bridges, wharves and other structures to reach the surf.(citation needed )If the timing is wrong they can hurt themselves or damage their equipment.   A large number of injuries, up to 66%, are caused by collision with a surfboard (nose or fins). Fins can cause deep lacerations and cuts, as well as bruising. While these injuries can be minor, they can open the skin to infection from the sea; groups like Surfers Against Sewage campaign for cleaner waters to reduce the risk of infections. Local bugs and disease can be a dangerous factor when surfing around the globe.

Falling off a surfboard or colliding with others, is commonly referred to as a wipeout.

Marine life

Sea life can sometimes cause injuries and even fatalities. Animals such as sharks,stingrays, seals and jellyfish can sometimes present a danger
         surfers do the "Stingray Shuffle," where they shuffle their feet in the sand as they head out to catch waves to scare away the stingrays that may be relaxing in the warm, shallow water

Rip Currents

Riptides endanger both experienced and inexperienced surfers. Rip currents are water channels that flow away from shore. Since these currents lurk in seemingly calm waters, tired or inexperienced swimmers or surfers can be swept away. A riptide usually has a width of forty or fifty feet. By paddling parallel to the shore, a surfer can escape the rip current

Seabed

 
       The seabed can pose dangers for surfers. If a surfer falls while riding a wave, the wave will then toss him around, usually downwards. Whether it'd be a reef break or beach break, plenty of surfers have been seriously injured or even died because of the great collision with the bottom of the sea. Seabeds can get very shallow, especially on beach breaks during low tide. Cyclops, Western Australia, for example is one of the biggest and thickest reef breaks in the world, with waves measuring up to 10 metres high. Yet the reef below is only about 2 metres deep.

source : www.wikipedia.org