Modern science has found that, in places where two different seas meet, there is a barrier between them. This barrier divides the two seas, so each has its own temperature, salinity and density. [Principles of Oceanography – Davis, pp. 92-93]
For example, the water in the Mediterranean is warm, saline and less dense compared to the water in the Atlantic Ocean. When water from the Mediterranean Sea enters the Atlantic over the sill of Gibraltar, it moves several hundred kilometers into the Atlantic, at a depth of approximately 1,000 meters with its own warm, saline and less dense characteristics.
The Mediterranean water stabilizes at this depth. [Principles of Oceanography – Davis, pp. 93]
The water of the Mediterranean Sea when it enters the Atlantic over the sill of Gibraltar with its own warm, saline and less dense characteristics, due to the barrier that distinguishes them. Temperatures are in degrees Celsius (ºC).
Meeting of the Mediterranean Sea and the Atlantic Ocean
Even at depths (indicated here by darker colors) up to 1,400 meters and at distances ranging from -100 to +2,500 meters, we find that both bodies of water maintain their individual temperatures and salinity.
Although there are big waves, strong currents and tides in these seas, they do not mix or break that barrier.
The Holy Qur’an mentions that there is a barrier between two seas that meet and do not transgress. God says:
Unleash the two seas, to meet. Between them, there is a barrier; neither commits a transgression. [Holy Quran 55: 19-20]
But when the Holy Qur’an talks about the divider between fresh and salt water, mention is made of the existence of “a forbidden division” with the barrier.
God says in the Holy Quran:
AND HE IS THE ONE WHO SET THE TWO SEAS APART: THIS ONE IS SWEET, TASTELESS, AND THAT ONE IS SALSA, BITTER. AND HE MADE, BETWEEN THEM, A BARRIER AND A COMPLETE PROHIBITION OF THEIR MIXTURE. [HOLY QURAN 25:53]
One may ask, why does the Holy Quran mention the partition when talking about the divider between fresh and salt water, but did it not mention this when talking about the divider between the two seas?
Modern science has found that in estuaries, where fresh (fresh) and salt water meet, the situation is somewhat different from that found in places where two seas meet. It was found that what distinguishes freshwater from saltwater in the estuaries is a “pycnocline zone with a marked discontinuity of the density that separates the two layers”. [Oceanography p. 242]
This partition (separation zone) has a different salinity than fresh water and salt water [Oceanography p. 244 and Introductory Oceanography pp. 300-301]
Meeting of two Oceans
This information was discovered only recently using advanced equipment to measure temperature, salinity, density, oxygen solubility, etc. The human eye cannot see the difference between the two seas that meet, and the two seas appear to us as a homogeneous sea. Likewise, the human eye cannot see the division of water in the estuaries into the three types: fresh water, salt water, partition (separation zone).