When I was a teenager (about 23 years ago) my brother and I decided that the hurricane off the Florida coast would give us some decent waves so we went surfing. The waves were impressive for a Florida boy - 6' or more above the surface of the water. As I mounted one I looked to each side and realized that we had a closeout - the wave was crashing immediately instead of rolling down the coast. In a closeout you just need to dismount - at least I didn't have the skill to ride a closeout.
I was only about 1/2 way up on the board so I just pushed it backward between my legs and dove forward and learned an important lesson about what happens to the water in front of a fast moving large wave. The water had been drawn down so that there was only about 12" under the surface - I hit the sand so hard with that wave driving me down that my front tooth was knocked out BY THE ROOT. The wave held me under, ground my face into the sand and pushed me toward the beach for what seemed like an eternity. About the time that I figured I was done - just about to gulp water for air, the wave let me up.
I remember standing on the beach with blood all over my face and chest, feeling my back reacting to having been bent double the wrong way - just stood there swaying, stunned.
I am convinced to this day that God decided he had some work for me to do - there were so many ways I should have been dead from that stupid move. Never did see a doctor about my back - I think it put itself together over the next 12 months (I went into the army a year later and seemed to do fine).