But there is always the risk of the oil spill. In 1989 the supertanker Exxon Valdez spilled tonnes of oil off the coast of Alaska. The oil spill from the supertanker spread over an area of 12,000 square kilometers. This created an enormous oil slick. Around 35,000 sea birds were killed in the oil slick.
Oil slicks poison sea life, clog up the feathers of birds and leak toxic chemicals into the sea.
We've been talking about oil spills and oil slicks. Oil is spilt into the sea by supertankers. It can also leak into the rivers from broken pipelines. Oil slicks poison sea life, clog up the feathers of birds and leak toxic chemicals into the sea. Detergents are used to break up oil slicks, but they themselves contain chemicals, which can damage wildlife, too.