It's an Anhinga, which looks (almost) just like a Cormorant! Both Cormorants and Anhingas lack oil glands. so their feathers are not water repellent. Although they can easily cruise and fish underwater (when both birds look like snakes with their heads above water), they have to get to a tree branch or land to dry their wings throughout the day -- or they would drown.
It's easy to mistake one large bird for the other. They both have duck-like webbed feet and they commonly roost and fish together. However, Cormorants have a curved, hooked bill and crystal-like blue eyes. Anhingas have a straight, long bill, longer tail, and small, white markings on their backs. Their eyes often appear red or a dull light green, as you can see from my photos below:
