A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying goods or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity, and tradition.
USS San Diego photographed 28 January 1915, while serving as flagship of the Pacific Fleet. Her name had been changed from California on 1 September 1914. Note two-star Rear Admiral's flag flying from her mainmast top.
A typical lobster boat off the coast of Maine. New Jersey boats are similar. Traps are hauled up by a hydraulic lift; steel plating protects the side of the boat.