The Mysterious Sailing Stones of Racetrack Playa. Deep in the heart of the California desert lies one of the natural world’s most puzzling mysteries: the 'sailing stones' of Death Valley.These move in long tracks along a smooth valley floor without human or animal intervention. They have been recorded and studied in a number of places around Racetrack Playa, Death Valley, where the number and length of travel grooves are notable. The force behind their movement is not confirmed and is the subject of research for which several hypotheses exist. Perhaps hollow earth relations