The far seas have always amazed man. The mysterious depths and their vastness is fascinating. To conquer the seas would mean the ability to control all trade, military expiditions etc. to the entire world.
However even until now, we barely understand the seas and the oceans in our own planet. We know better about Mars than about our own oceans. In the beginning man thought the world was flat and no one dared to venture too far from land.
The Americas became an isolated continent, with no connection to Asia, Europe and Africa. Though some evidence suggest a few sailors might have reached the Americas from Asia, but here we are talking about the vast majority.
In the Quran 1,400 years ago it was mentioned about the darkness of the seas. Now after man was able to find way to the depths of the oceans, we know that no light reaches below 1,000 metres. There is no light at all at these depths none whatsoever.
Or like utter darkness in the deep sea: there covers it a wave above which is another wave, above which is a cloud, (layers of) utter darkness one above another; when he holds out his hand, he is almost unable to see it; and to whomsoever Allah does not give light, he has no light.
There have been more people to the moon then to the Mariana’s Trench the deepest place on earth. The same verse also talks about waves upon waves in the seas. Layers of currents one on another.
This was not common knowledge to the Arabs living in the middle of the desert. There is no river in the entire Arabian Peninsula let alone be deep enough to know about deep currents.
How did Quran at that time without any devices know that there are multi layer of currents in the sea?
And certainly We have revealed to you clear communications and none disbelieve in them except the transgressors.