Deep Seas and Internal Waves

[Rayaan]

Watched the video a few times...kept expecting to see some barrier, you know..prohibiting partition and all that?
(pro-tip...Rayaan...the water mixes there as well..constantly. Apparently, Allah's magical "barrier" is inefficient, and ineffective.)

Pro-tip ... you may not be able to see the barrier, but it's there. And I know you have functioning ears to listen to what was being said, instead of using your eyes only. Thus your instinctive "But hey I didn't see any barrier, so nuh-uh it doesn't exist!" answer is invalid. You also ignored the other link that I posted.

What did you even expect the barrier to look like? A visible magnet or something? A giant floating bedsheet? An impenetrable layer of smoke?

To aid your visual perception, here's an original clip of the video with better quality:

http://www.youtube.com/watch?v=dHn80f3lAUs

In the first 10 seconds the diver swims under a salty water, and then you can see him coming out of it and entering a different layer of water (freshwater) which almost creates an illusion as if he is heading upwards into the air although, actually, he is still under water. At 35 seconds, he starts to swim from the freshwater back into the saltwater, during which the camera view becomes a littly blurry for a second as it crosses the barrier once again.

The barrier is called a "halocline" (or also called brackish water) which is a meeting of fresh and salt water as the narrator explains in the video. Then he says that the freshwater from the jungle flows over the heavier saltwater from the sea. This means that the freshwater and saltwater are divided (with one floating above the other) and the halocline acts as a natural barrier between the two.

So the halocline itself is the "prohibiting partition" because it keeps the fresh and salty waters separated: Below it is the denser salty water. Above it is the lighter freshwater. The meeting and mixing of the two layers happens only within the halocline, seen as a very thin body of rippling water, but outside of it the two kinds of water do not mix. And that's exactly why it is considered to be a barrier.