On March 24, 1989, the oil tanker Exxon Valdez struck a reef in Prince William Sound, Alaska. The ship's hull cracked open, and approximately 11 million gallons of crude oil poured into the pristine waters. The spill covered over 1,300 miles of coastline, one of the most remote and beautiful areas in North America. The damage to wildlife was devastating. An estimated 250,000 seabirds, 2,800 sea otters, 300 harbor seals, and billions of salmon and herring eggs were killed. Oil coated the feathers and fur of animals, destroying their ability to stay warm in the freezing waters. Thousands of volunteers traveled to Alaska to help clean oiled animals and scrub rocks along the shore. The cleanup effort cost over two billion dollars and took years. Even decades later, oil could still be found beneath rocks on some beaches. The disaster led to major changes in American law. Congress passed the Oil Pollution Act of 1990, which required oil tankers to have double hulls to prevent leaks. The spill also changed public awareness about the risks of transporting oil through sensitive ecosystems.