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It’s hard to visualise the true size of the Pacific Ocean until you look at it on a globe
(lemmy.today)
this post was submitted on 06 Aug 2026
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We'll find other life someday
I’m not a biologist, but wouldn’t ocean worlds be at or near the top of the list of planets most likely to host life?
https://nordpil.com/static/images/ocean_productivity_full.png
A picture's worth a thousand words. By far the most productive regions of the ocean are the shallow waters of the continental shelves. Maybe you could have an ocean world that was entirely shallow seas. But when I imagine an ocean world, I imagine abyssal depths spanning an entire planetary surface. Such a world would have far less ocean abundance than our own.
It wouldn't be a complete desert. Plenty of life does exist far from the continental shelves. It's just that these are the most productive regions of the ocean.
The problem with life is you need more than just water. Living things are mostly water, but the water is the boring part. And a lot of the essential building blocks of life tend to fall out of the water column as marine snow.
In shallow water, the depths that light can penetrate can also interact with the ocean floor. This allows more churning of vital materials. Plus there is a constant flow of new minerals and nutrients flowing in from the land.
In a deep ocean world? There would be very few minerals and nutrients available at any depth light could reach. Some would still work its way up through the action of currents, but nothing like the shallow waters.
And then you have to consider the nightmares Nature spawns, with terrors beyond any found in our oceans. A neat thing happens with oceans if you make them too deep. Pile enough water on top of water, and exotic high-temperature ices form under all that pressure. Some Super-Earths host oceans of scales beyond comprehension, but they are vast deserts made of water. If you kept piling water on Earth's surface, once the water got about 600 miles deep the exotic ices would start to form. This depth will vary based on the size of the planet, but for any given size, passed a certain point, the ocean has ice at the bottom.
And that is a problem for life. The water column is now cut off from the planet's crust. Volcanoes might periodically spew out some material through the ice shell, but we're already talking low-productivity worlds to begin with.
Now a shallow ocean world, a planetary continental shelf? THAT would be something to behold. But such worlds should be rare. Your ocean depth has to be tuned just right. On the scale from "mile's deep ocean" to "planetary desert," a planetary 100-foot deep ocean is just to the left of being a planetary desert.
So what I'm hearing is that Subnautica is off the table.
Subnautica? The game where literally the starting area has light reaching the ocean floor like that comment says?
I think you need to play it again
Where the planet is mostly abyss with super predators in it.
Where the planet is not covered by a 600mile deep ocean with super ice on the bottom, and has big areas with light reaching the sediment.
A planet where everything is deep ocean and frozen at the bottom does not provide enough minerals. But I don't know why this still needs explaining when the info was already available literally in the comment you replied to?
Read the words please.
In Subnauticas own lore, the caldera is a fluke alongside below zero's biome. The entirity of the planet otherwise is 'the abyss' which, now that I've read up on it - is not nearly as deep as I thought - that being only about 8 kilometers deep.
So I'm back to not being sure, there certainly wouldn't be any super ice but the nature of the abyss is still odd.
Yeah, most likely.
But I had already typed the comment before realizing that and the sweet sweet internet validation from upvotes doesn't make itself
Ocean worlds would be less likely to be able to make and control fire, which is likely one of the main reasons we have any technology at all.
It's reasonable to assume that a world that is completely covered by ocean has no technology or sapient life.
Agriculture also seems unlikely unless youre a sentient carp or something
Plants grow under/in water, why would it be impossible to plant them on purpose? Genuinely asking. And fish farms are a thing.
Also, pet peeve of mine: carps ARE sentient as they can perceive their surroundings using their senses. You probably want "sapient", being able to reason and think about those surroundings in more than just immediate reflexes.
Even more so, seaweed farms are a thing; 100% EXACTLY the thing the asked for.
But since most fire is ultimately used to heat water, couldn't a form of technology develop based on hydrothermal vents?
There would need to be an evolutionary drive to develop that tech. And in a water world there's little reason to. The main utilization of fire was to cook food. From there other developments occurred. That's not a thing that hydrothermal vents would be good at or easily utilized. An aquatic species would literally be inside the oven they cook with, and for little reason. Sushi is a thing we eat now. You also can't smelt metals underwater. So passing the threshold of utilizing basic tools is basically impossible.
Says the guy who never grew up on a water world. Bet you’re one of those foundation men! Space have you you ingrate!