Prince William Sound, large, irregular, islanded inlet of the Gulf of Alaska, S Alaska, E of the Kenai peninsula. It has many bays and good harbors; the large Columbia Glacier flows into Columbia Bay, in the N central portion. Shipping is focused at the port of Valdez, which is the southern terminus of the trans-Alaskan pipeline linked to Prudhoe Bay. Access to the interior of the sound is by highway and railroad. Fishing, forestry, and some mining are prevalent activities in the area. Valdez and Cordova are the largest towns on the sound. On Mar. 24, 1989, the Exxon Valdez hit a reef nearby and spilled 11 million gallons of oil into Prince William Sound. Clean-up efforts ensued; however, much of the region's wildlife was killed or endangered in subsequent weeks as a result of the environmental disaster.