The United States Third Fleet is one of the numbered fleets in the United States Navy. Third Fleet's area of responsibility includes approximately fifty million square miles of the eastern and northern Pacific Ocean areas including the Bering Sea, Alaska, the Aleutian Islands, and a sector of the Arctic. Major oil and trade sea lines of communication within this area are critically important to the economic health of the United States and friendly nations throughout the Pacific Rim region.

The structure of the United States Navy consists of four main bodies: the Office of the Secretary of the Navy, the Office of the Chief of Naval Operations, the operating forces, and the Shore Establishment.