Ocean currents greatly affect the Earth's climate by transferring heat from the tropics to the Polar Regions, and transferring warm or cold air and precipitation to coastal regions, where winds may carry them inland. The oceans are essential for transportation: Most of the world's goods are exported or imported by ship between the different continents. Oceans are also the major supply source for the fishing industry Offshore Oil, Gas and Mining Recreation and Tourism: Including fishing, boating, swimming etc. Disposal of Waste from Land: Including sewage, non-point sources, CO2 sink.