They´re called sneaker waves because they appear without warning, often surging high up on the beach with deadly force, and are impossible to predict. Sneaker waves also carry a large amount of sand that can saturate your clothes, weighing you down and making escape difficult if not impossible.
Oregon Parks and Recreation Department: State Parks Beach safety tips
via: Sneaker Waves: Beach Safety - GadlingWashington's Coast: Hazards - Sneaker Waves
Technorati Tags: