I was talking with my friend Kathi today. She and her husband like to scuba dive, and went to Manatee Springs to dive with the manatees. Apparently the manatees were all hanging out where the springs and the river came together, a murky area, and they wouldn't let them dive, giving some excuse about people fishing in that area, and there being a risk of getting stuck with a hook.
She thought it might be more because of gators in the river. Then she said something really interesting. She said she'd feel safe around gators if she were diving, because they don't attack under water: they can't open their mouths, or they drown.
I'd heard of gators grabbing prey then dragging it underwater to drown it, but not of actual underwater attacks. I've tried searching it, and while I don't see stories of underwater attacks, I don't see why they couldn't take place.
The Alligator Fact Sheet says "like a submarine preparing to dive, alligators also close hatches: a semitransparent membrane or third eyelid called a nictating membrane covers eyes; folds of skin close over the ears; muscles contract sealing the nostrils shut; and throat closes tight, enabling it to open its mouth and catch and hold its prey underwater without drowning."
According to The Gator Hole, "alligators have a specialized valve in their throat called a glottis that enables the gator to capture its prey underwater. However, in order to swallow its food and thus keep itself from drowning, an alligator must lift its head out of the water."
Another factoid: gators bite with 2,125 pounds of pressure compared with 940 pounds for a lion. This was measured by University of Florida researcher and (by my standards, anyway) madman Kent Vliet, who enjoys wrestling with them and watching them mate. Fascinating person.
Don't press your luck, Kathi.
[Illustration from American Alligator]