It is considered the worst oil spill worldwide in terms of damage to the environment. 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, originally extracted at the Prudhoe Bay Oil Field, eventually affected of coastline, of which were heavily or moderately oiled.