miracles in the Qur'an 1 - oceanography

My Muslim convert friend (whom we shall henceforth refer to as "Kevin") suggested I look at verses on oceanography, such as 25:53 on the separation of sweet and salty water, and 24:40 on the oceanic structure. These verses are not meant as an academic lesson apparently, but they do allude to history and science in a way that can be subjected to verification. I thus attempted to do just that...

"In answer to your suggestion that verse 25:53 alludes to a scientific phenomenon previously unkown/unknowable, it seems the idea was widespread since Aristotle:"The drinkable, sweet water, then, is light and is all of it drawn up: the salt water is heavy and remains behind, but not in its natural place.
For this is a question which has been sufficiently discussed (I mean about the natural place that water, like the other elements, must in reason have), and the answer is this. The place which we see the sea filling is not its natural place but that of water. It seems to belong to the sea because the weight of the salt water makes it remain there, while the sweet, drinkable water which is light is carried up." http://classics.mit.edu/Aristotle/meteorology.2.ii.html

SHAKIR: 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. (No particular reason for this translation. Please tell me what you consider to be the best one. I remember your being unimpressed with the one I had at x's and suggesting another, but I can't remember exactly which one you said...)
Again, I am doubtless less poetically/spiritually minded than you, but I fail to see the wonder of these lines. To suggest that, because this verse makes clear the author knew that light couldn't penetrate the ocean depths, it is suggestive of his divinity, is pushing it, isn't it? - any one in a boat in a deep, clear sea can see that one for themselves..As well as the well documented sponge-divers of the area whose tales of decreasing light as they descended would have been around. And there was plenty of poetry of the time which made reference to the dark depths of the oceans, which I shall be happy to quote, should you need further convincing. (And in any case, if he "has no light" why is he "almost unable to see it"? Surely the scientifically-minded Allah knows that that is impossible
To be continued...