We were using sleds to look for wreck site indications, such as anchors and cannons, during our trips to Cartagena, Columbia. I would probably find it a bit too scary to do that in areas known for Great Whites after an incident we had.
One day with two sleds in use I was on one sled and saw a pretty big nurse shark come zooming up off the 15-20' bottom like a shot, headed straight for the other sled jockey about 20 feet from me. (we were both on snorkels at the surface) I had no idea they (or Hal) could move so fast. He saw it just in time to respond appropriately by letting go of the sled to face the menace just before they could have touched, and it darted away as fast as it had approached. The only response I could come up with was to fill my mask with tears of laughter.
Good way to alienate friends.