00:00Did you know Earth has rivers flowing underneath the ocean?
00:04They aren't made of water. They're made of mud.
00:08When sand and sediment build up on the edge of the continent, it can suddenly collapse.
00:14That mixture of sediment and seawater becomes incredibly dense and heavy,
00:19much heavier than the clear water around it.
00:21So it sinks and starts to flow.
00:24Scientists call them turbidity currents, and they don't just trickle.
00:29These underwater rivers can travel for hundreds of miles at speeds up to 5 miles per hour,
00:35carving gigantic canyons in the seafloor.
00:38In fact, some of these underwater channels are bigger than the Grand Canyon.
00:44The Congo River has one that stretches for over 700 miles deep into the Atlantic.
00:49We live on a planet where even the ocean floor has rivers, waterfalls, and canyons.
00:56We just can't see them.