Jumping Off the Golden Gate Bridge

Why do most jumpers off of the Golden Gate Bridge, die? Is it because of the impact from the fall and salt water, which makes it like a cement wall? Does the fall angle and landing angle also become a factor? Does the cold 47F water also play a roll? Does the impact knock you out and this results in one actually drowning instead of death at impact?

I ask because, just yesterday, a high school teenager on a field trip from Windsor, California, went into the history books. His friends dared him to jump off as the class was walking across. He had jumped off bridges before. This was the ultimate challenge. While some  classmates watched in horror, others, in awe, the guy jumped and landed in the very cold SF bay. He is one of the very few to survive! My question is, why?

This was no suicide attempt, quite the opposite. In fact, the teenager almost landed on top of a surfer who was nearby. Thus, he was rescued quickly. He only suffered bruises on parts of his body and he was otherwise, fine. He and the most of the High School are now in counseling over it.

My theory is that he must have hit the water feet first, making for a small impact foot print, instead of landing in a prone position with face and back\front taking the brunt of the impact. This would cause a serious blow and most likely, loss of breath and unconsciousness leading to drowning quickly.