Like their sailing predecessors, power-driven naval vessels are designed for various operations involved in modern naval warfare. Contemporary naval fleets include aircraft carriers, cruisers, destroyers, frigates, mine craft, and a variety of transport and support vessels. Naval vessels generally have a slender hull shape that gives them greater speed than their merchant counterparts, which cannot economically sacrifice cargo-carrying capacity for speed.
One of the larger, more powerful fleets in the U.S. Navy is the Third Fleet based in San Diego, California. The purpose of the fleet, composed of a group of warships under a single command, is to protect U.S. interests in the Pacific Ocean.