as they extend out of the surf zone into deeper water, reaching speeds from and up to , which is faster than any human can swim. The water in the jet is sediment rich, bubble rich, and moves rapidly. The rip head of the rip current has long shore movement. Rip currents are common on beaches with mild slopes that experience sizeable and frequent oceanic swell. On the surfboard A longer surfboard of causes more friction with the water; therefore, it will be slower than a smaller and lighter board with a length of . Longer boards are good for beginners who need help balancing. Smaller boards are good for more experienced surfers who want to have more control and maneuverability. When practicing the sport of surfing, the surfer paddles out past the wave break to wait for a wave. When a surfable wave arrives, the surfer must paddle extremely fast to match the velocity of the wave so the wave can accelerate him or her. When the surfer is at wave speed, the surfer must quickly pop up, stay low, and stay toward the front of the wave to become stable and prevent falling as the wave steepens. The acceleration is less toward the front than toward the back. The physics behind the surfing of the wave involves the horizontal acceleration force (F·sinθ) and the vertical force (F·cosθ=mg). Therefore, the surfer should lean forward to gain speed, and lean on the back foot to brake. Also, to increase the length of the ride of the wave, the surfer should travel parallel to the wave crest. Dangers Drowning Surfing, like all water sports, carries the inherent risk of drowning. Although the board assists a surfer in staying buoyant, it can become separated from the user. A leash, attached to the ankle or knee, can keep a board from being swept away, but does not keep a rider on the board or above water. In some cases, possibly including the drowning of professional surfer Mark Foo, a leash can even be a cause of drowning by snagging on a reef or other object and holding the surfer underwater. By keeping the surfboard close to the surfer during a wipeout, a leash also increases the chances that the board may strike the rider, which could knock him or her unconscious and lead to drowning. A fallen rider's board can become trapped in