We’ve seen quicksand before in famous movies of yesteryear, and even recently in Youtube and Facebook videos. But this is a similar but different thing that puts the ‘quick’ in quicksand. This really weird yet entirely natural phenomenon occurred in Saudi Arabia’s Empty Quarter desert.
If you’re thinking it’s a moving river of sand, you would be partially correct. No one is quite sure exactly how it happened, but the leading theory is that it was created when a hailstorm dropped ice pellets that melted rapidly and “combined” with the sand to get it moving before it became mud. This would explain the strange characteristics and look of this river of sand.