Rare drone footage of the city with the "crazy" waters

Every six hours the waters change direction, in a rare tidal phenomenon:
Chalkís or Chalkida is the chief town of the island of Euboea in Greece, situated on the Euripus Strait at its narrowest point.
A special tidal phenomenon takes place in the strait, as strong tidal currents reverse direction once every six hours, creating strong currents and maelstroms.