Sailing stones

Sailing Stones are boulders that glide across the dry lakebed of Racetrack Playa within Death Valley National Park in California. These rocks weigh between a few pounds and more than 600 pounds and leave long trails behind them on the pale clay surface.

Gold prospectors first saw the trails of moving rocks in the early 20th century and discussed them in mining camps across the region. Researchers began mapping their movements in the 1950s and finally solved the mystery in 2014 using cameras and GPS devices.

Scientists spent decades developing theories about the stone movement, ranging from magnetic fields to extraterrestrial forces, until research revealed the true mechanism.

The moving rocks sit about two miles south of the Grandstand parking area on the playa and can be reached on foot across the flat desert floor. The walk crosses hard clay with no shade and can become very tiring in summer heat.

The rocks move only during a few winter days when thin ice forms on shallow water puddles and wind pushes the ice sheets across the wet clay. Some trails stretch over 800 feet (250 meters) and remain visible for years until new rainfall erases them.