The most valuable of the marine mineral resources is petroleum. About 15% of the world's oil is produced offshore, and extraction capabilities are advancing. One of the largest environmental impacts of deep sea mining are discharged sediment plumes which disperse with ocean currents and thus may negatively influence the marine ecosystem. Coal deposits known as extensions of land deposits , are mined under the sea floor in Japan and England.
Deep sea mining is a relatively new mineral retrieval process that takes place on the ocean floor. Ocean mining sites are usually around large areas of polymetallic nodules or active and extinct hydrothermal vents at about 1,400 – 3,700 m below the ocean’s surface. The vents create sulfide deposits, which contain valuable metals such as silver, gold, copper, manganese, cobalt, and zinc. The deposits are mined using either hydraulic pumps or bucket systems that take ore to the surface to be processed. As with all mining operations, deep sea mining raises questions about potential environmental impact on surrounding areas. Environmental advocacy groups such as Greenpeace and the Deep sea Mining Campaign have argued that seabed mining should not be permitted in most of the world's oceans because of the potential for damage to deepsea ecosystems and pollution by heavy metal laden plumes.