For some reason I don't know the specifics of; cuts that come from coral, oysters, barnacles and the like tend to get inflamed and infected fairly easily.
We as kids would run the tide. There was a very large culvert that went from the river into the marsh land on the other side of the road.
When the tide went out we would grab a piece of lumber and ride through the culvert. The inside of the culvert was covered with barnacles, if we misjudged the tide we would hit the top or sides of the culvert. A full moon tide was wild as the water was twice as fast as usual.
At times we would come out of the culvert bleeding like we had been filleted.
Hurt, you betcha, the salt in the water made the pain worse. We never got infections from the slice and dice game, we put Honey on our wounds and waited a few hours before going home, our mothers would have freaked out had they any idea what we were doing.
The only time I got an infection was when one day we were out stomping about on the mud flats and I stepped on a razor clam. I had to get antibiotics as my foot ballooned up really nasty.