Stepped on a big, nasty piece of broken glass (I assume, never actually saw what got me) in the water at a beach, and cut my foot up really badly when I was about 9. Ended up with 29 stitches in the great toe (mostly here, almost severed it, sliced my tendons clean through) and sole, and sometimes I still get phantom pains shooting through the scars. Hurray for nerve damage.
I wouldn't go in the water without an old pair of shoes on, or aquasocks (when they came out) for years to follow. I'll wade barefoot now, but it still really spooks me thinking about what nasty, jagged things might be lying just under the silt. Mostly, I'll tread water, or float on my back/belly rather than put my feet down and walk. If I put my feet down, I feel the area out cautiously, and keep my feet planted on that one spot.
Maybe not completely irrational (there really are sharp things to watch for: stones, glass, boards that got torn off of docks by the ice and still have 6" nails sticking out of them that get waterlogged and sink, and especially broken muscle shell fragments which can be razor sharp) but it still bothers me that it bothers me.
P.S.- blogblogblog