A unique, pretty, and misunderstood bird. People often confuse them with the smaller, more wide spread Cormorant. Both breeds need to dry after swimming, neither has oil for their feathers.
Anhinga hunt different also. Their bill is very sharp, and pointed. Rather than grab fish with their beak, they actually spear their prey.
This is a male with a black neck and blue ‘eye shadow’.
Something else I have noticed. If you click and enlarge the image you can see tiny gnats / black fly swirling around his head. Most photographs that are close will have this. Might be their diet of fish.