One of the properties of seas that has only recently been discovered is related in a verse of the Quran as follows:
"He has let loose the two seas, converging together, with a barrier between them they do not break through."(Quran, 55:19-20)
“And it is He who has released the two seas, one fresh and sweet and one salty and bitter, and He placed between them a barrier and prohibiting partition” (Quran 25: 53)
This property of the seas, that they come together yet do not mingle with one another at all, has only very recently been discovered by oceanographers. Because of the physical force called "surface tension", the waters of neighboring seas do not mix. Caused by the difference in the density of their waters, surface tension prevents them from mingling with one another, just as if a thin wall were between them.
