The Exxon Valdez oil spill occurred in Prince William Sound, Alaska, on March 24, 1989. Exxon Valdez, an oil supertanker owned by Exxon Shipping Company bound for Long Beach, California struck Prince William Sound's Bligh Reef, 1.5 mi (2.4 km) west of Tatitlek, Alaska at 12:04 a.m. and spilled 10.8 million US gallons (257,000 bbl) (or 37,000 tonnes) of crude oil over the next few days.The Exxon Valdez spill is the second largest in U.S. waters, after the 2010 Deepwater Horizon oil spill, in terms of volume of oil released. Prince William Sound's remote location, accessible only by helicopter, plane, or boat, made government and industry response efforts difficult and made existing response plans especially hard to implement. The region is a habitat for salmon, sea otters, seals, and seabirds. The oil, extracted from the Prudhoe Bay Oil Field, eventually affected 1,300 miles (2,100 km) of coastline, of which 200 miles (320 km) were heavily or moderately oiled.

Prince William Sound (Sugpiaq: Suungaaciq) is a sound of the Gulf of Alaska on the south coast of the U.S. state of Alaska. It is located on the east side of the Kenai Peninsula. Its largest port is Valdez, at the southern terminus of the Trans-Alaska Pipeline System. Other settlements on the sound, which contains numerous small islands, include Cordova and Whittier plus the Alaska native villages of Chenega and Tatitlek.