The Exxon Valdez oil spill was a major environmental disaster that occurred in Alaska 's Prince William Sound on March 24, 1989. The spill occurred when Exxon Valdez , an oil supertanker owned by Exxon Shipping Company , bound for Long Beach , California, struck Prince William Sound 's Bligh Reef , 6 mi (9.7 km) west of Tatitlek, Alaska at 12:04 a.m. The tanker spilled more than 10 million US gallons (240,000 bbl) (or 37,000 tonnes ) [1] of crude oil over the next few days. [2]