Double-crested Cormorants are a frequent sight on the bird shaped sprinkler pipe floats in South Florida water retention ponds.

They perch, often with their wings spread to dry them after a swim to catch a tasty fish.

When they are swimming, they'll plunge their head into the water and vanish beneath it:

Then, sometimes a surprising distance away, their head will pop back out of the water, often with a fish. Sometimes they toss the fish a bit up in the air before they swallow it; I'm still working on getting that picture.

I've seen two diving birds down here in South East Florida, the Double-crested Cormorant and the Anhinga. When they are too far out on the water it's hard to tell them apart when only their head and neck are sticking out, but if you can get close enough to see, you can tell them apart by their beaks. The top of the Cormorant's beak curves down, and the Anhinga's beak is pointy to the tip.