I’ve done this before, swim with nurse sharks. Was not my idea of fun but a snorkle buddy wanted to do it when we were in Belize. They are harmless to humans because they have tiny mouths and few teeth, they actually suck up/inhale their tiny prey. Still, they look like sharks so my primal instinct was to get out of the water. They feel like sandpaper.
MATTHEW'S ISLAND 
So what do these nurse sharks actually eat? Curiously yours, bob jennings in toronto canadiancomposer@gmail.com
I was told at the time that they were vegetarians but that turns out not to be true. They’re bottom feeders and eat shellfish (crabs, spiny lobsters, urchins) and some small fish. Problem for me was that when we did the “swim with the nurse sharks” thing it was late afternoon and the light was dimming and they all looked like shadowy great white sharks to me.