The episode opens with what looks like one of Earth’s Poles …
… with a pair of madcap Australian(?) adventurers who chronicle their explorations with a tablet(!).
It’s difficult to know if this is a TV show they’re doing or a podcast.
Nevertheless, disaster:
It seems like an easy deal. Just load Thunderbird 4 into a pod of Thunderbird 2 and off they go.
Except, in a very neatly-done twist …
… it’s revealed they’re actually on a moon of Jupiter!
There seems to be some actual science in this …
… but I’m skeptical about it being totally correct. Being trapped under ten miles of water, what would the pressure be like?
How could the adventurers’ suits survive that? And what about the difference in atmospheric pressure versus underwater pressure?
Maybe this is where they pull out the Dramatic License. I don’t know.
We can let some things go by unquestioned.
Something new: Thunderbird 4 loaded into Thunderbird 3 for an extraterrestrial underwater rescue!
A very modified Thunderbird 4:
Of course the rescue is accomplished. Not without some hitches, of course.
And with one surprise:
But I will shut up about that. Spoiler. Which leads to a hilarious ending:
A good story. But with one problem the entire damn series has: It’s a cartoon.
I don’t feel the sense of danger that the miniatures and puppets of the original series had.
In the end, there’s just nothing remarkable or astonishing about CGI.
I can’t help wondering what this would have been like done with Supermarionation.
But this production company tends to post-process even the miniatures so that they look like CGI and not physical objects. A tragedy.
Tell you what. Here’s an idea. Do a dream episode where the dream is all done with puppets and miniatures.
Let’s see if they’d have the guts and, above all, the skills, to do it.
Ahem:
Stargate SG1 – Puppet Universe
Previously here:
Mike Cane's Atomic Supermen 
Note that on a small moon the pressure under ten miles of water would be a fraction of what it would be on earth.
But what about the influence of Jupiter’s gravity? It would just affect the water flow, as in the episode?
I haven’t seen the episode but so I’m only relying on your description. I would expect very strong tidal flows if the moon is rotating due to Jupiter’s presence (much much stronger than the effect of the Moon on Earth) and I think that the main effect Jupiter might have on the underwater pressure would be mediated by that distortion of the shape of the oceans.
Yes, the episode had the currents being strong due to Jupiter’s gravitational influence.
So which moon is this? For example, Ganymede is the largest moon in the solar system. From the little I see of the episode, Ganymede could be a possible location. Wikipedia tells me g on Ganymede is 0.146m/s^2. So if I estimate correctly, 10 miles deep in an ocean on Ganymede would be like 1.46 miles deep on Earth, everything else being equal (density of water assumed the same, etc). If on Europa, the equivalent depth would be slightly (<10%) less.
“On Jupiter’s moon Europa Gordon’s favourite explorers…”
https://en.wikipedia.org/wiki/Thunderbirds_Are_Go_(TV_series)#Series_2_.282016.29
So maybe a pressure equivalent to 1.3-1.4 miles below the ocean surface on earth then, assuming similar density of water of course. Btw, there is no atmospheric pressure on Europa to speak of, so only pressure due to the water above, but that’s a detail compared to the 1.35 mile depth.
Just to clarify: 0.146 is a fraction without units; the surface gravity on Ganymede is 1.428 m/s^2 or 0.146g, where g, Earth’s surface gravity, is 9.8 m/s^2.