However...

However, some earlier observations may have unknown the darkness increase with depth in a sea, the earliest such observations are reported to have taken place in 16 th century, i.e., Ferdinand Magellan in 1521 attempted to measure the depth of the Pacific Ocean. He used a 2,400-foot weighted line, but did not touch bottom.

[78] In another report: Scientific deep-sea exploration can be said to have begun when French scientist Pierre-Simon Laplace investigated the average depth of the Atlantic Ocean by observing tidal motions registered on Brazilian and African coasts circa the late 18th or early 19th century. However, the exact date of his investigation is unknown. He calculated the depth to be 3,962 metres (12,999 ft), a value later proven quite accurate by echo-sounding measurement techniques.

[79] [80] The new findings from a team effort involving MIT and several other institutions, highlights the effectiveness of internal wave in sea are produced and are compared with the surface waves: In new research, both in the ocean as well as in the largest-ever laboratory experiments to investigate internal waves, has solved a longstanding mystery about exactly how the largest known internal waves, in the South China Sea, are produced.

Seen in cross-section, these waves resemble surface waves in shape. The only difference between an underwater wave and the water around it is its density, due to temperature or salinity differences that cause ocean water to become stratified. Though invisible to the eye, the boundary between colder, saltier water below and warmer, less-salty water above can be detected instrumentally.

That boundary layer can resemble the ocean’s surface, producing waves that reach towering heights, travel vast distances, and can play a key role in the mixing of ocean waters, helping drive warm surface waters downward and drawing heat from the atmosphere. Because these internal waves are hard to detect, it is often a challenge to study them directly in the ocean.

[81] In year 610, Quran talks about the total darkness produced by sea waves, one over the other, producing such darkness to human eye that when he holds out his hand, he almost cannot see it [24:40]- thereby revealing the mysteries of deep-sea darkness, well before the above-mentioned scientific findings. The Rain forms when from Sleet in the upper atmosphere: Allah Says: He is the One Who Shows you the lightning Causing fear and hope and Raises the heavy cloud.