U-boats were capable of going down further than 200m. They were less concerned about waves and more concerned about depth charges.
Except...
Fuel.
Underwater they'd use batteries and those didn't last very long before having to be topped up again by the diesel-generators (which cannot run underwater because air).
Plus, water resistance exceeds air resistance and therefore sailing on the surface is faster and costs less of a limited fuel supply.
All they might want to do is dive deep enough to not be bothered by them pesky waves.
Wavey ship motions are generally considered annoying.
Unless they
know there be enemies around.
That's when you go deep and go silent.
But they couldn't exactly afford to do that ALL the time.
Nowadays perhaps yes; with
nuclear subs.
Not with a diesel.
Meanwhile, looking at that video
Indiana Jones Steven Spielberg: Disagreement with George Lucas changed fourth movie shows that Spielberg is out, Disney is in - yes, they've taken over yet another franchise.
That's not exactly news.
Disney bought
Lucasfilm.
YEARS ago.
That deal didn't just include Star Wars, but also Indiana Jones and Willow.
So what?
One problem is that neither Indiana Jones nor Harrison Ford are getting any younger.
Not actually a problem.
Indiana Jones goes beyond Harrison Ford, no matter what anyone might claim.
At least, not without some trickery for Ford and a plot device for Jones:
Better than that horrid rumour of TIME TRAVEL!
Along with the EXCESSIVELY LIKELY & EXCEPTIONALLY cliche trope of "killing off the weary old hero".
PoTC also belongs to Disney so they're perfectly entitled to transfer a plot device from one franchise to another...
What's PotC got to do with it? That's irrelevant.
The Fountain of Youth is a common myth fully in the public domain.
ANYONE is entitled to use it, reuse it and use it yet again.
PotC took it from outside Disney in the first place.
"On Stranger Tides" was originally a novel by Tim Powers.
Spoiler alert 1: it contains MANY similarities to the 4th PotC movie of the same name (this is no coincidence).
Spoiler alert 2: Jack Sparrow isn't in it (this is no coincidence either).
"Disney" has used the Fountain of Youth already a long, long time before.
Carl Barks used it in a very classic Scrooge McDuck story.
Steven Spielberg is on record for confirming that Carl Barks' work was always one of the main inspirations for Raiders.
This is pretty apparent even from just the jungle temple opening scene alone, which copies not just 1 but
two devices from another such Duck comic.
And for good reason.
Scrooge McDuck basically IS an Indiana Jones!
In some ways, he's BETTER than Indiana Jones.