" The Dark Depths of the Seas And Internal Waves

Or [the unbelievers' state] are like the darkness of a fathomless sea
which is covered by waves above which are waves above which are
clouds, layers of darkness, one upon the other. If he puts out his hand,
he can scarcely see it. Those Allah gives no light to, they have no light.
(Qur'an, 24:40)
In deep seas and oceans, the darkness is found at a depth of 200
meters (660 feet) and deeper. At this depth, there is almost no light, and
below a depth of 1,000 meters (3,280 feet) there is no light at all.65
Today, we know about the general formation of the sea, the characteristics
of the living things in it, its salinity, as well as the amount of
water it contains, and its surface area and depth. Submarines and special
equipment, developed with modern technology, have enabled scientists
to obtain such information.
Human beings are not able to dive to a depth of more than 70
meters (230 feet) without the aid of special equipment. They cannot
survive unaided in the dark depths of the oceans, such as at a depth of
200 meters (660 feet). For these reasons, scientists have only recently
been able to discover detailed information about the seas. However,
that the depth of the sea is dark was revealed in the Qur'an 1,400 years
ago. It is certainly one of the miracles of the Qur'an that such information
was given at a time where no equipment to enable man to dive into
the depths of the oceans was available.

In addition, the statement in Surat an-Nur 40 "…like the darkness
of a fathomless sea which is covered by waves above which are
waves above which are clouds…" draws our attention to another miracle
of the Qur'an.
Scientists have only recently discovered that there are sub-surface
waves, which "occur on density interfaces between layers of different
densities." These internal waves cover the deep waters of seas and
oceans because deep water has a higher density than the water above
it. Internal waves act like surface waves. They can break, just like surface
waves. Internal waves cannot be discerned by the human eye, but
they can be detected by studying temperature or salinity changes at a
given location.66
The statements in the Qur'an run parallel precisely the above
explanation. Certainly, this fact, which scientists has discovered very
recently, shows once again that the Qur'an is the word of Allah. "

― Harun Yahya , Allah's Miracles in the Qur'an