Combat Swim Stroke

"The Combat Swim Stroke (CSS) is a relaxing and super-efficient variation of the side stroke, developed by and taught to the United States Navy SEALs. The CSS is a mix of sidestroke, freestyle and breaststroke. It allows the swimmer to swim more efficiently and reduce the body's profile in the water in order to be less likely to be seen during combat operations if surface swimming is required." ~ From Wikipedia

In this video, a coach breaks down this swimmer's CSS for the viewer. Note: it helps to be very tall.