Alaska's remote Bogoslof Island is only 169 acres, a third the size of the average American farm. And its highest "peak" is just 490 feet, half as tall as the Eiffel Tower.

Like other Aleutian islands, it's swarming with sea lions. But it's what's below the surface that sets Bogoslof apart.

The tiny island is the summit of an active, underwater volcano that extends down 5,500 feet, with its base on the floor of the Bering Sea.