Exxon Valdez Spill

Just after midnight on March 24, 1989, a huge oil tanker ship called the Exxon Valdez hit a rock reef in Prince William Sound, Alaska. The ship's metal hull tore open, and over the next few hours, about 11 million gallons of thick black oil poured into the cold ocean water, enough oil to fill more than 17 Olympic-sized swimming pools.

- What happened the night the Exxon Valdez tanker crashed - How the oil spill hurt animals and the ocean in Prince William Sound - How people worked to clean up the spill - What new rules were made afterward to try to stop it from happening again

The Exxon Valdez was carrying oil from Valdez, Alaska, to California. Its captain, Joseph Hazelwood, had left the ship's bridge in the hands of a less experienced officer, and the huge tanker drifted off its normal path and struck Bligh Reef, a well-known rock formation that ships were supposed to avoid. The crash ripped open 8 of the ship's 11 cargo tanks.

The oil spread across more than 1,300 miles of Alaska's coastline. Scientists estimate the spill killed around 250,000 seabirds, 2,800 sea otters, 250 bald eagles, and up to 22 orca whales, along with billions of salmon and herring eggs. Oil coats a bird's or otter's fur and feathers, which normally trap air to keep them warm and afloat, once coated in oil, animals can freeze, drown, or get sick from swallowing the oil while trying to clean themselves.

More than 11,000 workers, along with volunteers, spent months scrubbing oil off rocks and washing animals like sea otters in warm, soapy water. Even so, scientists later found oil still buried in Prince William Sound's beaches decades later. In 1990, the U.S. Congress passed the Oil Pollution Act, a new law requiring oil tankers in U.S. waters to have a stronger double hull, basically two layers of metal instead of one, to make it much harder for a crash to tear the ship open and spill its cargo.