Some oil lies below the ocean floor and can seep into the ocean through cracks. As much as 1.5 million barrels of oil may enter the ocean from natural seeps each year. When these leaks occur, as when spills occur, natural organisms and chemical processes act to break down the oil over time. This process is called natural bio remediation. Oil is harmful to shellfish, finfish, marine mammals and waterfowl who live near the spill.
Oil spills are ugly and are expensive to clean up.
In addition, damage to fisheries places a hardship on those who make their living by fishing. When oil enters the ocean it quickly begins to change and disperse. Though oil is toxic, it becomes less so with time. Winds and waves help spread and disperse the oil. Some oil will evaporate.