Hycean worlds are planets which bridge the gap between rocky and gas giant planets. They have atmospheres high in hydrogen and vast oceans with perhaps no dry land at all. How could the local sentient life develop space flight? My only idea is they have jellyfish/coral organisms which could metabolize hydrogen to float which they could engineer to form ships, but that feels like cheating.

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    $\begingroup$ VTC: Needs More Focus. This feels way too broad. What's they're tech level? What advances have they made? Asking us to invent the entire technological tree leading up to space flight for your civilzation definitely violates the Book Rule. If this does't seem fair, then this has a high liklihood of being a duplicate of the various "how does technology develop on my water planet?" questions. Did your species not evolve to extract metals from the ocean floors? Or have you decided to crowbar sentience and sapience onto a planet where neither has a fighting chance? $\endgroup$
    – JBH
    Apr 30 at 4:39

1 Answer 1


It might be impossible

Sorry to say it, but it's likely impossible. Hydrodgen-based floating obviously doesn't work outside of the atmosphere, and without dry land, good luck using metallurgy ─ or even fire. It's possible that a water world could develop sentient beings, but not ones with much technology.

  • $\begingroup$ Thanks for being honest $\endgroup$
    – Joe Smith
    May 1 at 21:55

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