It certainly looks like an aircraft carrier, especially one of the old Essex class carriers from World War II. But its purpose is to land by helicopter a battalion of Marines along with all their gear. They normally would have mostly helicopters with some Harrier jets. I believe this class of ship is now retired with a later generation taking their place. The new classes of this type of ship have a deep well in the stern area where smaller amphibious ships can be stored then the area is flooded and the smaller ship can head to shore with their Marines. You were lucky to photograph this ship, especially since it is retired. Most of the current amphibious assault ships are either in the Persian Gulf , Indian Ocean, and Medit. Sea or refitting back in the U.S.