Directed by Desmond Saunders
Teleplay by Alan Fennell
First UK Broadcast – 25th October 1964
You know how it goes – you book a lovely holiday with your mates full of sun, sea, and sand, only for your boss to cancel it and send you on a mission to the centre of the Earth. Oh, what’s that? You’re not familiar with that issue? Well, this is Stingray, so you’d better get used to that sort of thing happening. Subterranean Sea is one of those points in the series when the production team have just had to throw up their hands and declare, “Who cares if it makes sense? Let’s just have fun with it and hopefully the people watching at home enjoy it too.” And, d’you know what? That sounds like just the right attitude to me.

The episode opens with a jaunty piece of music which tells you everything you need to know about the next 25 minutes. It’s big and bombastic, but it’s also fun and all a bit tongue-in-cheek. The underwater base looks suitably uninspiring and grey in order to provide a contrast with the Stingray crew’s ambitions for a colourful holiday which will be revealed in a moment.

The whacking great question mark on the diagram over there indicates that subtlety really isn’t the name of the game here. Scientific equipment has been strewn about all over the place to really drive home the fact that this is a laboratory – many of the props were likely borrowed from Venus’ lab aboard Fireball XL5 and other sets like it.


Andrews and Prescott are two scientific geniuses leading a drilling project to get through the Earth’s mantle… or is it the Earth’s crust? Andrews says, “we’re through the Earth’s mantle,” and Prescott then asks, “What’s beneath the Earth’s crust?” Maybe Andrews meant “we’re through to the Earth’s mantle?” Because the answer to the question, “What’s beneath the Earth’s crust?” is pretty obvious… it’s the Earth’s mantle… which we know… and have known since the year 1909. Anyway, never mind what the question is, the answer is sea water. Yes, below the crust or the mantle or whatever it is there is apparently an ocean. Not as silly as it sounds according to countless recent articles from publications like Discovery and New Scientist which do indeed make bold proclamations about a massive ocean beneath the ground – although if there is an ocean in the Earth’s mantle it’s not a big blue wobbly one as this episode suggests, but instead lots of H2O deposits inside all the minerals down there.

Prescott and Andrews remind us all that their shocking new discovery is terribly important, and they want to get the WASPs on the case as fast as possible. Now, question, is this really a job for the WASPs? It’s not exactly a matter of world security is it? Surely a scientific expedition would be more appropriate?


But never mind all that tosh, we’re goin’ on ‘oliday! Wahey! Troy’s packed all his essentials very neatly so one must assume Phones’ suitcase is stashing nothing but booze. Troy’s bedroom is unchanged from its appearance in The Ghost of the Sea although the pattern on the wall behind the bed has shifted ever so slightly because Troy’s incredibly weird about his decor like that. Phones is back in that fever dream he calls a shirt, which we last saw in Count Down.


For Marina and Atlanta that side-splitting old gag about women not understanding the concept of travelling light is wheeled out. The baggage labels reveal they have previously visited such glamorous locales as “ENGLAND” and a “CONSULATE.” Atlanta’s blouse was previously worn by Venus in the Fireball XL5 episode, Space Vacation.

Back with Troy and Phones, an ominous call comes in from Commander Shore ordering everyone to the control tower. Troy reckons its just to wish everyone a bon voyage. Troy clearly doesn’t know the commander very well.



The gang arrive, very much unprepared to have the wind completely taken out of their sails. Shore does his best to sound unhappy with his decision to cancel their furlough. Remember the time before 2020 when most people didn’t know what the word “furlough” meant?


A drastic change in lighting, hair, makeup, and possibly puppet head for Altanta suggests that one of her close-ups in this scene was reshot later. She makes a rare reference to Shore having other vessels at his disposal which is frankly a bit of a tease seeing as Stingray is the focus of every bloomin’ episode.

Now Atlanta has her thoroughly cheesed off face on, a head we rarely see. Maybe that that earlier close-up that was reshot originally featured the frowner head? It’s worth noting that a behind the scenes photograph exists showing various Atlanta heads being tested, clearly taken during the filming of this particular scene…

And here it is. Atlanta isn’t too thrilled here about her lack of a body. This test shot’s existence does seem to suggest that Altanta’s frowner head was a matter of discussion during the filming of this scene.

Anyway, regardless of Atlanta’s interchangeable heads, Shore orders the Stingray crew to report to the undersea mantle boring base… boring being the right word for it. Time for another short history lesson. In 1961, not a million years away from when this episode was produced, Project Mohole was launched to drill down and obtain a sample from the Mohorovičić discontinuity (the bit inbetween the crust and the mantle) – a plan drawn up to match the ambition of the space race. To cut a very, very long story short, they managed to do a little bit of drilling off the coast of Mexico, and then the funding fell through. Nevertheless, it was this project which no doubt formed the inspiration for this episode. So, going back to my earlier quibble about how far down Prescott and Andrews were actually trying to drill, I suppose the answer is probably not too dissimilar to what scientists were trying to achieve in real life – to reach the Moho boundary some 4 miles beneath the sea bed. Glad we’ve cleared that up.

Why is there a random bit of wood going across the floor between the wall and the main control panel? Surely Commander Shore’s chair would have trouble with that?


Stingray is launched without too much fanfare – the crew are too fed up for music. Oink won’t be joining them again this week. He’s working on his new album. Troy cannot conceive of a good reason why anyone would want to drill down through the Earth’s crust – a feeling shared by the U.S. congress in 1966 when they gave up all support of Project Mohole and terminated it before Phase II could begin.



It isn’t long before Stingray arrives at the base, and enters through an ocean door – the flexable sliding panels of which can clearly be seen in motion. This is, in fact, exactly the same ocean door we see opening inside Stingray’s pen when the craft launches. Skids extended, Stingray touches down on a platform, conveniently exactly the right size for it.

Prescott confirms that they were absolutely definitely just drilling through the Earth’s crust so all my complaining earlier was unncessary. This lab set is decorated, rather unusually, with the set of human-sized air tanks used for live action close-ups in The Ghost Ship. Also visible is the coffee trolly previously seen in Shore’s bedroom in The Ghost of the Sea, and a random bit of pipe that was previously sticking up from the floor in Preston’s office in Sea of Oil. Phones has just chucked his hat on the floor because he’s already fed up, while Marina leans casually on something she probably shouldn’t be leaning on.

Troy is shocked to learn that there is an ocean under the crust. He also wonders why Stingray would possibly be involved… hmmm… what connection could Stingray have to a recently discovered ocean? I wonder, I wonder. Clearly Troy’s brain is still on vacation.






Here’s a lovely and understated bit of business while Prescott and Andrews explain the plot to Mr. Thicky. Andrews starts by wearing his specs, there’s a cutaway to Troy which therefore allows Andrews to appear to remove his spectacles because he’s a puppet lacking in fine motor skills. Troy responds in kind by reaching to put his hat on, so we cut to a close-up of Prescott, and then cut back to Troy with the hat firmly on his head.

Another jaunty musical outburst from Barry Gray as we ponder the question mark for a bit longer because it’s a mystery and nothing says mystery like a whacking great question mark. I’m sure scientists have giant question marks slapped all over the place to help them focus on the task at hand. “What will I have for lunch today?” – slap a giant question mark on the fridge and find out. “Is my husband sleeping with the maid?” – slap a generously-sized question mark on his underpants.


So Stingray is going to be lowered two miles down an elevator shaft to reach the new ocean. Considering the drilling didn’t finish all that long ago, they’ve made fast work of building that elevator! Back projection footage whizzes past the window to indicate the speed of their descent. Phones continues to be sour about the vacation issue. I like Phones when he’s snippy and bitter, it suits him.

A really nice little moment between Troy and Marina here. He tries to tap into her knowledge of the ocean to see if this subterranean sea is known to the underwater people. It isn’t, but it was worth a shot, and just asking that question reminds us all of why Marina is a valuable asset to the WASPs. Also, wow, that’s an impressive hairdo.



As Stingray goes down deeper, footage of the depth gauge from The Big Gun is reused to indicate that their depth is indeed increasing, even if the numbers seem a bit meaningless. In order to indicate that things are hotting up, steam and/or smoke begins to fill the shaft – proximity to the Earth’s core and all that. So heat is a bit of a concern. Pressure isn’t discussed at all. I guess after the events of The Big Gun and the resulting improvements apparently made to Stingray, such things are no longer worth talking about… or it was too much of an inconvenience to the plot to bother mentioning it…

Troy unenthusiastically declares that they are heading into the unknown. Don’t worry, I promise they do all perk up and take a bit more interest in all this stuff shortly.



As Stingray dives into the darkness, the depth gauge gives up. Apparently “16” (miles, fathoms, inches?) is considered by WASP engineers to be more than enough for any domestic situation. Troy has to explain to Phones that they’re deeper than anyone has gone before… because apparently that wasn’t obvious.






Oi, poor people, have you bought a colour television set or are you still watching in black and white like a sucker? Yes, Stingray still hasn’t quite gotten over the novelty of filming in colour and wants to make it loud and clear with this inconsequential moment where the crew are dazzled by some glass, fluorescent rocks which look suspiciously like regular rocks that have been painted in a hurry. Troy is apparently able to magic up a pair of sunglasses out of no-where because he’s supposed to be on holiday in case you’d forgotten.



Then, things start to get really wild as Stingray gets caught up in a strong current, excellently realised on screen with a rolling backdrop behind the model, and dust being blown straight at it. Phones wrestles with a single lever to indicate that the craft is out of control, which is further emphasised by some dials darting about all over the place.




Things get really bad when Stingray crashes spectacularly onto the bed of this new ocean, and the crew are sent flying. The appropriately bumpy camerawork does briefly reveal the top of the set as Phones falls. Marina really gets knocked about as she’s thrown into a safety rail and then crashes to the floor. I understand that Supermarionation puppets are inherently quite heavy anyway, but nevertheless a good job has been done of making Marina’s fall look suitably dramatic, rather than like a puppet is just being swung around the set.

The large model of Stingray finally comes to rest at the bottom of the slope, debris floating around like crazy in the water tank to match the chaos happening on the set. The synchornisation between what happens on the model set and what happens in the water tank in front of the camera is really quite remarkable at times.


Things don’t look great for the Stingray crew as we head into the commercial break. Can Troy’s day possibly get any worse?

Fading back in, and something is definitely a bit different here…



Everyone just about survived the crash. Doesn’t Phones have a funny looking ear, or is that just me?



Time for a bizarre continuity error now as Troy attempts to get the motors working. Before the crash, we saw a close-up of Phones’ hand operating a lever. Now, we have what is supposed to be Troy’s right hand using that same lever. A few problems though – it’s his left hand, it’s shown coming from Phones’ chair, and it’s dressed in a diving suit from later in the episode. Cut away to Troy with his frowner face on, and all of sudden it’s now that shot from earlier which may be using the correct uniform, but is still Phones’ left arm instead of Troy’s right.

It soons becomes clear that there is no water anywhere near the motor. This is a bit of a problem for a submarine. Goodness the large Stingray model looks magnificent buried in all that rubbish though. The rear fins are distinctly bent out of shape but I can’t work out whether that’s supposed to be damage, or if those are control surfaces which are supposed to be able to move around like that.

Troy is not a fan of dry land. This is a great shot from outside the cabin which really makes it look like Stingray is tilted at an angle.



Captain Tempest is full of bright ideas today and decides the only option is for them to go and have a wander around outside, just in case the water is hiding from them behind a rock or something… I don’t know, I assume they’re continuing their exploration mission this way, but I would probably spend a bit more time assessing the situation from the safety of my craft first. Troy accurately points out that there is neither air, nor water outside so Marina will have to wear a mask like the rest of them. It’s a neat observation, although whether there actually is air down there is probably a question for a scientist, not the aforementioned Mr. Thicky. Come to think of it, why isn’t there some sort of scientific boffin on the Stingray crew? Supercar had Beaker and Popkiss, Fireball XL5 had Professor Matic, Thunderbirds had Brains. None of the main Stingray chracters have so much as a GCSE to share between them. There are hints later on in the show that Atlanta is sort of the brainy one, but particularly when going on missions like exploring uncharted oceans, taking a bonafide scientist along would probably be a good idea.




Watching the hatch open in the dry and the Stingray crew walking around in their underwater gear does genuinely feel quite bizarre. It all feels incredibly alien and weird, despite the fact all this action usually takes place in the dry anyway, just with a water tank in front of the camera. It just goes to show how incredibly convincing the swimming effects usually are.




Look, I’ll level with you, there isn’t a lot to say about the next few minutes of this episode. It’s just Troy, Marina, and Phones walking through the desert landscape, and the camera lingering on all the weird and, let’s not forget, colourful plants on display down here. Don’t get me wrong, it looks magnificent, and I think the build up of tension as the crew explore this strange new world works well, there just aren’t that many observations I can make about it except for, “hey, look at that plant” or, “doesn’t Troy look thick as he plods about in the sand?”



What with the steaming ground, the live action lizard, and the red hot rocks, the heat soon becomes a matter of conversation. Troy reckons they must be close to the centre of the Earth… someone draw Mr. Thicky a diagram will they? They’re about 1,800 miles from the centre of the Earth. Sure, I’ll buy that it’s hot, but they’re not exactly close to the core.

Marina stops everything because she hears something nasty heading their way… maybe she’s more in-tune with the ocean, or maybe she just has better hearing than the other two…

I have no idea how the production team managed to make the refraction heat waves visible on camera but it really does look jolly hot!




The water’s coming back! Goodness me, we are keeping busy today. The sweaty team start running. Some live action feet are used because puppets aren’t terribly good at sprinting – although it must be said that some of those walking shots earlier were great. A veritable torrent gushes forth and sweeps aside the unusual desert plants.





Steaming hot water begins to the fill the landscape as the characters’ running slows down to wading and eventually turns into diving. Troy wildly flaps his arms around in front of him because he likes to make a song and dance over everything. The puppets get absolutely soaked. Presumably the set was rebuilt inside the water tank in order to achieve these shots. It looks like the live action inserts were filmed in the studio too. That must have been a dangerous amount of water to have sloshing about all over the place.



The water swirls around and the soundtrack really does a lot to elevate the scale of the chaos going on here, adding even more power to the force of the current. The Stingray crew are back to swimming underwater as we’re used to seeing them, and Marina slams the airlock door shut with enormous satisfaction. Shame the commotion messed up her hair.



Troy and Phones struggle hard to get Stingray afloat, Don Mason once again giving it all he’s got. Fortunately, our favourite submarine is soon back up and running and oh my it looks lovely.



A brief trip back through the land of psychedelic adverts for colour television. Marina’s wild, long, flowing hair definitely gives her a bohemian vibe. Troy looks like a cool cat enjoying the summer of love in those shades. Phones looks like he’s going to be sick.

I love a shot of Stingray with its lights on and there are quite a few good ones in this episode.

While Marina tidies up the bookcase, Troy and Phones try to make sense of what just happened. As I’ve already mentioned, they’re not scientists so they try to keep everything in simple terms. Troy reckons that what they experienced was a tide like any sea would have, it’s just rather forceful. The desert was a result of the heat drying out the sand. The tide must have turned so quickly that the water wasn’t even visible on the horizon before they heard it coming. It’s a terrifying notion.

Now Phones has a bit of a difficult job ahead of him trying to locate the elevator shaft again with nothing but a sound scanner bouncing a signal off the Earth’s crust above them.

Oh, and their air is running out… even though the gauge for air pressure is actually increasing… wait, what? Can someone sciencey explain this one to me? Is it a mistake or am I being Mr. Thicky now? More air pressure means more air molecules which means more air, no? And anyway, science aside, for the purposes of storytelling having a gauge counting down to zero, instead of counting up, would have been much more dramatic.




Three hours later, coffee is being had, the gauge says the air is getting thicker which is apparently bad, and the machine is still making the same noise until finally it isn’t and that means everyone is saved! Hooray!



A very brief shot of light shining through the water is lifted from last week’s episode, Emergency Marineville. Stingray heads towards the light as they struggle to breathe through all that high air pressure. On the surface, Stingray has found itself in a lagoon in paradise. How convenient. Presumably that means there’s a direct route from the surface right the way down through the Earth’s crust to the subterranean sea. Prescott and Andrews will be delighted to learn that they’ve wasted all that time and money on a drilling operation when they should have just taken a tropical holiday and gone snorkeling.

The jammy blighters can’t believe their luck.

It makes for a gorgeous shot, but Troy’s parking job does leave a bit to be desired.

Yes, Phones brought that terrible shirt with him just on the off-chance the holiday was back on. Otherwise, it’s a charming scene. A happy and musical Marina strums the guitar while Troy smokes a cigar and enjoys a picnic. A local beach dweller inexplicably dances for them.

I say dances, it’s not exactly ballet. The flowers and greenery, and that delightful outfit make for a very colourful moment. Pure spectulation but could this puppet be using a heavily modified Marina head? The shape is similar although the eyes have been swapped out along with possible plasticine modifications to the nose and lips. Stranger things have happened.


Spare a thought for Atlanta who receives a tossed off postcard from Troy while she’s stuck at work with her father.

Troy couldn’t give a monkey’s, and the episode ends with us reflecting on much Altanta’s been screwed over by all this. Don’t worry, she’ll get a holiday soon… sort of.
Blimey, I’m short of breath after making it through that episode. It’s a really wild ride but I loved every minute of it. The core premise is just the kind of whacky, out-there scientific theorising that Supermarionation shows are great at. It’s in the same vein as trying to collect a piece of the sun in the Thunderbirds episode Sun Probe, or Fireball XL5 just accidentally breaking the light barrier in the episode Faster Than Light. It’s daring but it’s exciting and jolly good fun. And while the science is taken with a pinch of salt, the danger and the threat of the unknown is treated very seriously. All the business with the vacation is just a loveable layer to the episode which makes the characters all the more delightful. Barry Gray wraps all these elements up in a score which stands out superbly as one of his more unusual for the series, but totally inkeeping with the off-beat nature of the episode. If Emergency Marineville represents the series following the rule book to make a classic, Subterranean Sea is the production team taking the rule book and drawing childish doodles all over it, and I love that.
Next week, we’re actually taking a short break! I know, rubbish, right? Yes, I’m jetting off to a deserted island full of picnics, cigars, and dancing girls. Maybe I’ll send you a postcard just to rub it in. But when I get back to the blog on Friday, September 2nd, we’ll all be taking a trip to Scotland and paying a visit to see the unbelievable… Loch Ness Monster! See you then!
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Further reading:
www.filmedinsupermarionation.com by Century 21 Films Ltd.
Filmed In Supermarionation by Stephen La Rivière. Third edition published in 2022 by Century 21 Films Ltd.
Stingray: Adventures In Videcolor by Andrew Pixley. First published in 2022 by Network Distributing.
Massive ‘ocean’ discovered towards Earth’s core by Andy Coghlan. Published in 2014 by New Scientist.
There May Be a Massive Ocean Beneath the Earth’s Surface by Reuben Westmaas. Published in 2019 by Discovery.
How an ill-fated undersea adventure in the 1960s changed the way scientists see the Earth by Byrd Pinkerton. Published in 2021 by Vox.
As always Jack, great review, it is epic. I do like this episode because it makes a chnage from seeing villains in the plot all the time. I can’t wait for Loch Ness Monster either, that one is always great favourite.
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