There are several causes of ocean pollution including oil pollution, marine debris, toxic materials, and ocean dumping and mining. Oil pollution is not only caused by large devastating tanker spills, it is also caused through runoff from land and industrial wastes which find their way to the ocean through drains.
Marine Debris often comes in the form of our trash which has been washed into the ocean after heavy rain or floods. A particular danger to marine wildlife are nets which have fallen of boats or plastics which can be swallowed and caught in an animals digestive system.
Toxic materials accumulate in the ocean in the form of mercury, dioxin, PCBs, PAHs, Radioactivity. Both dumping and exploitation of ocean resources cause ocean pollution also.