I Have Often Seen Pictures And Films,

taken in the Amazon,

where about 8 miles from Manaus, Brazil, the almost cream coloured waters of the Solimoes River meets the coffee coloured waters of the Rio Negro River, at any point where two of these rivers join, their density is so different that they will not mix for several miles, the Amazon River is formed at the point these two rivers join together, I had always thought that this natural phenomena was pretty unique,

until I read about the resort town of Skagen you can watch the same thing happening the city is the northernmost point of Denmark, where the Baltic and North Seas meet, the two opposing tides in this place can not merge because they have different densities, the area where the Baltic and the North Sea come into contact is quite shallow and so the contact face is relatively small, there is of course some mixing but it is quite minimal due to the difference of the density, 

it is also helped by the fact that the Baltic is not tidal which keeps most of its water within the Baltic basin and this water is constantly being reduced in salinity by the rivers which drain into the Baltic, were it not for that small opening into the North Sea the Baltic would be a giant fresh water lake, so I now know there are two areas where waters mix and look amazing, I guess there must be many more.