The process whereby mapping technologies are used to produce highly detailed images of the sea floor. Ever since large ships began sailing the oceans, there has been a need to know what the sea floor looks like. At first this need was simply to avoid dangerous shoals upon which a ship could wreck. In the mid-1800s, the need increased with the first laying of transocean communication cables. World War II and the initiation of submarine warfare elevated the need to a matter of national defense, and mapping of the world's ocean floors was greatly accelerated. The vast body of information accrued by this effort went far beyond aiding militaries. It also led to the theory of plate tectonics, the backbone of modern geology that explains volcanoes, earthquakes, mountain chains, and many other Earth features. At present, sea-floor mapping is also aiding a variety of societal endeavors. High-resolution images of the sea floor are being used to locate and manage marine resources such as fisheries and oil and gas reserves, identify offshore faults and the potential for coastal damage due to earthquakes, and map out and monitor marine pollution. The greatly improved sea-floor imaging is providing information on what processes are affecting the sea floor, where these processes occur, and how they interact. See also: Marine geology