British explorer Captain James Cook made the European discovery of Prince William Sound in 1778. Today, the 25,090-square-mile (65,000-square-kilometer) passage southeast of Anchorage, Alaska, is the focal point of an ongoing political and environmental issue: whether oil can be safely transported in extreme climates without seriously threatening terrestrial and marine habitats or the recreational, agricultural, and industrial interests of the region.

Prince William Sound is bordered on the north and west by the Chugach and Kenai mountain ranges, on the east by the Copper River, and by the Hinchinbrook Islands on the south. Ten percent of its area is open water, with depths ranging from 492-2,952 ft (149-895 m). The remainder consists of shallow coastal waters, shoals, and reefs. The combined 2,980 miles (4,800 km) of mainland and island shoreline are home to more than 200 species of birds, among them approximately 3,000 bald eagles. Ten species of marine...