I’m a sucker for a story with an underwater setting, regardless of whether the genre is horror (for which I’ve already offered some recommendations!), fantasy, or science fiction. In the sci-fi category, Jules Verne’s Twenty Thousand Leagues Under the Sea is the titan of the deep, and while I’m a huge fan of that book, it’s probably the first title that most people think of when they hear “underwater science fiction.” Here are five other works of aquatic sci-fi to explore—some plunging to the depths of Earth’s oceans and others set in the stranger seas of far-off planets.
“Surface Tension” by James Blish (1952)
The setting of “Surface Tension” isn’t actually an ocean, a sea, or even a lake—it’s a puddle. The story starts with a spaceship having crash-landed on a distant planet called Hydrot. The ship is just one of many sent from Earth in an attempt to colonize the galaxy, but while Hydrot is fairly Earth-like, it can’t support any life as large as humans. The crew is doomed to die, but they do have the technology to mold subsequent generations to the alien environment.
The bulk of the story follows a group of tiny aquatically-adapted humans as they strive to explore the world beyond their home puddle. To them, the puddle is their whole world, but human curiosity is a trait that has been retained, and so they put their minds together in an attempt to break the surface tension of the water and see what lies beyond.
Sphere by Michael Crichton (1987)
Sphere kicks off with the discovery of a massive spaceship at the bottom of the Pacific Ocean. How long it’s been there and where it came from are mysteries that can only be solved by putting boots on the ground… or rather, fins in the water. A team of scientists and U.S. Navy officers are sent down to live in an underwater habitat close to the spaceship so that they can study and explore the vessel up close.
While Jurassic Park (1990) remains my favorite Crichton book, Sphere is probably in second place. The intriguing premise is backed up by a thrilling and twisty plot that left me not wanting to come up for air. It’s the kind of book that reads like a movie. Crichton also excels at crafting a claustrophobic and creepy environment at the bottom of the ocean, expertly ratcheting up the tension as the pages fly by.
Starfish by Peter Watts (1999)
Another sci-fi story set under the waves of the Pacific Ocean is Starfish, which largely takes places around the Juan de Fuca Ridge. The heat generated by underwater geothermal vents at the bottom of various oceans is being used as an energy source and small crews of people—known as Rifters—are needed to maintain the power stations.
Such a job requires extensive physical modifications to allow the human body to handle the deep-sea environment, but bio-mechanical implants aren’t all that it takes to be a Rifter. Only those who are already used to stress and strife, primarily abusers and the abused, are deemed to have the necessary temperament—and even then, some people crack under the pressure.
Starfish is a dark story—both in terms of setting and psychology. Being thousands of feet below sea level isn’t a normal place for humans to exist, and the plot explores how such a dangerous and isolated environment could impact the human mind.
A Darkling Sea by James L. Cambias (2014)
A Darkling Sea takes Star Trek’s Prime Directive—that is, not interfering with the development of alien civilizations—and flushes it out to sea.
The story is set on Ilmatar, an ocean planet covered in a layer of ice that is thousands of feet thick. Humanity has cored through this ice and set up a station on the ocean floor in order to study a native species that shows signs of higher intelligence. The scientists would love to make contact, but they’ve been forbidden by another alien race, the Sholen, who fear that the humans would mess with the Ilmatarans’ natural development. But that all goes out of the window when arrogant media star Henri Kerlerec sneakily dons a stealth-suit to view the Ilmatarans up close, and then ends up being dissected.
Told via POVs from all three species, A Darkling Sea explores the utter mess that unfolds when they come into conflict—be that intentional or not. Even though most characters are trying their best, misunderstandings lead to problems that grow progressively more serious as the story develops.
“Freediver” by Isabel J. Kim (2025)
Technically, “Freediver” is set on Earth, but it’s not Earth as we know it. All of the planet’s oceans are only a few hundred feet deep, after which there is a meniscus-like portal that leads to a slice of space forty-five billion light years away. Telecommunication cables that connect the continents have been hung in this section of space and although that means they’re safe from the elements on Earth, they are occasionally damaged by space debris. Glasser and Crane are a two-man team whose job it is to repair the cables, with the aid of a subship that is capable of short dives beneath the waves.
The sci-fi concept of “Freediver” may feel otherworldly, but the character work is firmly grounded. Through Glasser and Crane, Isabel J. Kim explores themes of loneliness and connection, as well as the psychology behind why people do dangerous jobs—which in this story involves diving to the bottom of the ocean and then space-walking in the void between stars.
I’ve been thinking that underwater settings in sci-fi stories feel a bit underrepresented in my reading, but maybe I just need to put more effort into seeking these narratives out. To help me along my way, I’d love to hear your recommendations in the comments below, be they short stories or full-length books!
Half the Day is Night, Maureen McHugh. Not my favourite of hers, but it fits the bill.
I came here to recommend this — I liked it quite a bit.
I read this amazing short story or novelette a while back, something that I think was written in this century, but I can’t remember the title or author (there’s a chance it was Alastair Reynolds or someone in that ballpark). It was told from the perspective of an alien that lived in the subglacial ocean of a moon like Enceladus or Titan, where the dominant force was buoyancy rather than gravity, so the viewpoint character’s definitions of up and down were the reverse of ours — the “ground” was the underside of the ice crust, the core of the planet was “overhead,” dense objects or dead bodies that lost buoyancy ascended to the heavens, etc. I believe the main character interacted with a human explorer and there was some difficulty understanding each other’s points of view. It was a fantastic worldbuilding exercise, worthy of Hal Clement (though I think it was too recent to be Clement), and I wish I could remember what it was called and who wrote it.
Blowing my own horn, there’s my 2009 Star Trek: Titan novel Over a Torrent Sea, which I believe to be the first full novel set on a Leger-type Ocean Planet, a body that’s roughly half water by mass so that its rocky core is surrounded by thousands of kilometers of high-pressure allotropic ices with a few dozen kilometers of ocean on the surface, with no land of any kind and increasingly crushing pressures as you get deeper until the water gradually transitions to slush and eventually solid ice. (Ian McDonald featured an Ocean Planet briefly and peripherally in his 2008 novella “The Tear,” beating me to it by a year or so, but OaTS is still the earliest novel-length, in-depth treatment I’m aware of.) I largely rewrote the novel from an original spec novel I wrote in the 1990s, so it’s perhaps the purest hard science fiction story of any of my Trek novels.
My original spec novel was set on a more conventional water world with islands, but when I saw Star Trek: Voyager: “Thirty Days,” about a spherical “ocean” artificially maintained in space, I spent years trying to figure out a way that a whole planet of pure or nearly pure water could plausibly exist so I could rewrite my novel to take place on such a world. I could never find a sensible way to do it, but Leger Ocean Planets are about as close as you can get. (My best handwave was a chunk of neutron star matter that had accreted a bunch of ice around it, but I now understand that even if such a thing could have existed, it would still have been mostly high-pressure allotropic ices with only a relatively thin liquid ocean on the surface.)
I’ve found it (or, at least, the one I was thinking of, but I’m certain it’s the one you’re thinking of as well). It is “War, Ice, Egg, Universe” by G David Nordley, first published in 2002. I encountered it in the anthology Strangest of All edited by Julie Nováková and published in 2021.
War, Ice, Egg, Universe at Clarkesworld
Strangest of All at Nováková’s website
Yes, that’s it! I’d thought it was in a library book, but I actually have Strangest of All on my computer, and had forgotten that I did. Thanks!
Frustratingly, I think about that story every now and again because it was so good, but I can’t remember the title, author, or when I read it. If I turn it up, I’ll be sure to let you know.
Maybe Alastair Reynolds’ A Spy in Europa?
No. I just read it. It was not the story that Christopher described. 😥
Someone else recently highlighted “The Deep Range” by Arthur C. Clarke. It’s primarily, although not completely underwater. https://en.wikipedia.org/wiki/The_Deep_Range
I would recommend Startide Rising by David Brin (1983), complete with uplifted dolphins.
The Russalka Chronicles, Jonathan L. Howard: “Katya’s World” and “Katya’s War”. Undersea human colonies on a watery planet. Teenage protagonist, might be considered YA. The technological aspects are nicely developed. I enjoyed these quite a bit. (Note: planned as a trilogy, and the ending is obviously unresolved.)
OOP – and that search brought me to a 2013 Tor review by Niall Alexander.
I’d suggest The Man Who Lived in Inner Space, by Arnold Federbush.
what a cool title…
Adrian Tchaikovsky’s Children of Ruin shows (as the title foreshadows) what can happen if naturally inquisitive octopuses are genetically modified and become technologically advanced with no guardrails.
I’m of the opinion that octopus and squid may be more intelligent than humans, and the only reason they don’t have a civilization is that they only live about three years, so they basically never make it past being toddlers (which is really sad to think about). I suspect the only evolutionary change they’d need is a longer lifespan, and they’d end up running the place. (Which was a premise I used in my audio novel trilogy Tangent Knights.)
I strongly recommend James White’s The Watch Below (1966), it’s half set on a sunken WW2 US to UK cargo ship, and half on an aquatic alien fleet fleeing their no-longer-habitable world. The 2 stories are interleaved, with the humans struggling to survive among air pockets, and the aliens leading the fleet as they head toward a distant hopefully-liveable world.
First thing that came to my mind as well. A much darker claustrophobic novel than anything else White wrote. The only disappointment for me was the ending that tied things up too neatly.
The Mountain in the Sea by Ray Nayler is a really good book that explores octopus intelligence and culture. It is not entirely underwater (partly because the octopi walk can onto the beach at times and use weapons to attack people).
LOVED the spooky underwater scenes in this book. Even though a lot of the book takes place above water, I’d agree this octopi book counts (and I would recommend it for anyone who is okay with more ominous vibes than character or plot development).
The plural is octopus, or octopuses, or octopodes. The “-pus” is Greek for “foot,” so it doesn’t follow Latin plural rules.
If we’re going to be pedantic, “octopi” is an acceptable plural. According to Merriam-Webster, “Octopi is the oldest plural of octopus, coming from the belief that words of Latin origin should have Latin endings.” SO before being pedantic about something that is completely unnecessary because we all understood the meaning to be plural octopuses… maybe fact check yourself. :)
Harry Turtledove’s THREE MILES DOWN (Tor, 2023). It’s 1974 and the Russians have lost a submarine in the North Pacific Ocean. The US naturally wants to investigate further, but without letting the Soviets know. So they disguise their team as a scientific expedition.
That’s what happened in our timeline. Except here, we learn there’s an alien ship next to the sunken sub.
Nixon, the CIA, shag carpeting, all things early seventies, plus underwater aliens!
Sphere is my all-time favorite Crichton novel! It’s so ominous, it’s stuck with me for decades. I’ve never heard of any of these other books, I so agree it’s an underrepresented aspect of SFF! Added a couple to my TBR. :)
A couple books that aren’t totally focused on being underwater but do have that as part of the narrative:
-The Quantum Magician by Derek Künsken — this is mostly about a Homo quantum savant who does… quantum magic for a heist; pretty dang cool in and of itself. BUT another species of humans adapted to live in a high-pressure underwater environment after a terraforming accident (Homo eridanus) is also featured, who have a unique disgust at their own adaptations and living situation…
-Provenance by Ann Leckie — this is primarily about a young politician trying to rescue a political exile to gain clout with her family. However, there is a delightful alien species (the Geck) who live on a water planet, and all their cultural oddities in relation to that are so fun to read about. The political exile has ties to the Geck, so we get a fun look into their culture. Also, there is a Radchaii ambassador to the Geck who is not a fan of her position. (This is especially fun if you’ve read the Imperial Radch trilogy by Leckie–Provenance takes place in the same universe, though not the same galaxy…)
Agree on Peter Watt’s Starfish. That was a powerful story, although it fell apart a bit near the end.
Suzanne Palmer’s Diving the Deep, not only under water, but one of my favorite re-reads. From Goodreads blurb: “The trail leads them to Enceladus, where Fergus plans to go undercover to the research stations that lie beneath the moon’s thick ice sheet deep in a dark, oppressive ocean.”
Dragon in the Sea, Frank Herbert. Of *course* we don’t have subs hunting each other over oil–right?