Good story, relative to philosophy, but I suspect this is also fiction, and fiction has a major quirk: suspension of disbelief; i.e., making the story plausible when dealing with facts that may make the story unbelievable. Fiction wants to be believed, or the reader may lose interest, because fiction is, well, not truth. The trick is being able to blur the line between fiction and reality such that the story remains believable.
So, I am a recreational scuba diver, but I have never been deeper than about 40 meters [130 ft].Such people represent about 2% of the world population, so, not that common of an activity. That plays in your favor, suspension-of-disbelief-wise. Most enthusiasts have a single, 80 cru. ft tank, [3,000 psi] which, at 10m [33 ft] will last about an hour. And the standard wetsuit will only endure the effects of pressure to a little beyond that 40m before other protection is needed, so, going "miles down" suspends disbelief. The average depth of the oceans to a floor is about 3,700m [12,000 ft]. Granted, these are factors that, given the small percentage of divers in the world, again, work in your favor, but, there are guys like me who will not be held with rapt attention to the story.
Then, there are necessary decompression stops on the way back up - necessary about every 20m [65 feet] to prevent the bends [O2 bubbles rising out of suspension in the blood, which is fatal without such stops]. For example, once at about 25m [82 ft] I decided to see if I could rise to the surface, making one decompression stop on the way [one should always have a depth gage] on a single breath, constantrly exhaling all the way up. Such is necessary, even with the stop, to prevent O2 bubbles resulting in the bends. I succeeded, though belng a dangerous matter. It was a thrill to realize it could be done.