HistoryMind-BlowingAn earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.2951k
AnimalsMind-BlowingDuring spring tides, a tidal bore called the Pororoca rolls up the Amazon River, creating a continuous wave up to 4 meters high that can be surfed for over 12 kilometers. The phenomenon is strongest between February and March when Atlantic tides push ocean water upstream against the river's flow.153k