An Exploded Bay

West Thumb on Yellowstone Lake was formed by a massive explosion one hundred twenty-five thousand years ago, leaving a shoreline with crater-like contours and an underwater profile dramatically deeper than the rest of the lake. The area remains thermally active, with hot springs, mudpots, and geysers steaming and percolating along the shore, and temperature gauges recording high heat flow in the lake bottom sediments. In winter, holes in the thick ice mark hot spots in the lake bed where thermal features bubble up, and otters often fish in those melt holes.

Wyoming · United States