It is ordained that the seas Allah (SwT) has let forth shall have barriers that they may not overpass for reasons devised by nature:
‘’He has let fort two seas, that they should meet together. There is a barrier between them which the do not overpass’’ (55: 19, 20)
It is well-known fact that French scientist Jacques-Yves Cousteau famous for his underwater researches discovered, what is already laid down in the Holy Verse. Cousteau discovered that the Mediterranean waters and Atlantic Ocean differ in terms of their chemical and biological composition.
Cousteau’s work took him to the Straits of Gibraltar in order to explain this phenomenon. His conclusions are interesting and stay in tune what Holy Quran revealed 14 centuries back.
Cousteau concluded that unexpected fresh water springs sprout forth from Southern (Moroccan) and Northern (Spanish) coasts of the Gibraltar. These mammoth fresh water spouts gush towards each other at angles of 45 degrees forming a reciprocal dam like teeth of a comb.
Due to this fact, the Mediterranean and the Atlantic cannot intermingle. Indeed, subsequent to this assessment, Cousteau was amazed upon being shown the Holy Verses. He was filled with admiration for the Quranic revelations and accepted Islam.
It is a known scientific fact that seas bear more living beings than does land. With the almost infinitely numerous tiny organism we call plankton, their countless flora and fauna of all kinds, the seas constitute a divine handiwork in their own right.
It is also obvious that different organisms will inhabit different environments. This is precisely the reason why nature does not allow the seas to mix.
The marine biology of one sea may not survive in the environment of another sea, hence the barrier devised by nature.