Cormorants are divers, and can spend quite a while underwater hunting for fish. When on the surface they swim quite low in the water. The lower image is a group in a typical pose drying their wings on the shoreline (they often use a post). There are a few young ones amongst them, with pale chests. I am used to seeing Cormorants sat roosting in trees, so it makes a nice change to see them in such a spectacular location out at sea.