Harbor, a sheltered body of water, usually an arm of the sea, in which ships are protected from high seas, storms, and other natural forces. Harbors near large cities normally have commercial ports for handling incoming and outgoing passengers and goods. They may also have shipyards, naval bases, bulk cargo terminals, and a variety of industries lining the shores. Some harbors, however, are small and are used only by fishing and pleasure craft; others are used only during storms.
Ideally, a harbor is almost surrounded by protective land and is free from high winds, waves, fog, and ice. Its water has a small tidal range and is deep enough to accommodate large ships at all times, both in the channel and near the shore. There is good bottom ground for anchoring, abundant anchorage space, and enough room for large ships to maneuver. In a good harbor the entrance is wide, straight, and deep, so that congestion and delay are avoided by arriving and departing ships. There is adjacent flat land for wharves, warehouses, and other port facilities.
A natural harbor is one formed by nature. It requires improvements and maintenance by man. Boston, New York, Newport News, San Francisco, and Seattle are United States cities with excellent natural harbors.
An artificial harbor is one built by man. The most common type is formed by building one or more breakwaters and dredging the enclosed area as needed. Los Angeles, Charleston, and nearly all the port cities on the Great Lakes, including Buffalo, Cleveland, and Chicago, have harbors of this type. Another type of artificial harbor, used in areas with extreme differences between high and low tide, is the tidal basin, or sea basin, consisting of an enclosed area entered through locks.
Harbors may also be classified according to their geographic settings. An open-coast, or roadstead, harbor is a relatively unprotected body of water in which ships are anchored offshore and are usually loaded and unloaded by boats called lighters. A lagoon harbor is a sheltered stretch of water separated from the sea by one or more long, narrow, offshore islands. Harbors on river estuaries are called estuary harbors; those farther upstream are called river harbors.