Ten years ago, March 24, 1989, the oil tanker Exxon Valdez ran aground on Bligh Reef south of Valdez, Alaska, precipitating the largest oil spill in North American history and forever altering the image of Prince William Sound as a largely untouched ecosystem.

In the days that followed, roughly 41.6 million liters of oil leaked from the crippled vessel, eventually soiling more than 2,000 km of coastline in Prince William Sound and the Gulf of Alaska and killing thousands of creatures inhabiting the area. In the three-year clean-up effort that followed, Exxon spent $2 billion recovering oil from the afflicted areas and in 1991 agreed to pay $900 million into a restoration fund jointly managed by the federal and state governments.

Prince William Sound today shows little sign of an environmental disaster: In an area that has changed little in thousands of years, dense conifer forests rise into rugged, snow-capped mountains; glaciers that stretch for kilometers inch forward and fjords like giant fingers jut out into the sea.