In 2008, a NASA scientist dropped 90 rubber ducks into a hole in Greenland’s fastest-moving glacier; none returned, deepening the mystery of where its meltwater travels

NASA Jet Propulsion Laboratory researcher Alberto Behar lowered 90 yellow rubber ducks into a moulin on Greenland's Jakobshavn Glacier in September 2008. The toys were meant to travel with meltwater through the glacier and eventually emerge somewhere downstrea