About midway along the north shore of Prince William Sound the Columbia Glacier, one of Alaska's largest, reaches the water in a wall of ice, calving icebergs continuously. Like most glaciers today it is rapidly retreating, with its terminus now 10 miles (16 km) from its location twenty years ago.

Every few years the floating ice choking the area in front of the glacier suddenly flushes out and the terminus can be approached in boats. But usually it is like this - miles of icebergs with the glacier seen in the distance.