You can see the erosion marks on the bottom of the karsts. It has been estimated that the karsts have been exposed to tidal current for about 3 million years. The tides are extreme but very gentle, absolutely no waves and very slow current. I can see why it took so long for the erosion to get to where it is. To the right of the karst is one of three floating villages in Ha Long Bay to the left are local fisherman.