[bodhi_mind]

Basically the equivalent of a lighter than “air” craft but in a different fluid. I wonder if there’s a word for a craft that controls its buoyancy regardless of medium?

[javajosh]

An Archimedes craft.

(I made this up just now).

[gigiggufh]

Fluid is a Latin root, so why not "fluidostat" on the model of "aerostat"?

[4gotunameagain]

because -stat is a Greek root.

merriam-webster

   borrowed from French aérostat, probably back-formation from aérostatique "of aerostatics," with -stat (after héliostat heliostat) taken as the Greek agentive element -statēs "one who causes to stand" — more at -stat

[pvaldes]

> I wonder if there’s a word for a craft that controls its buoyancy regardless of medium

sperm whale

[moffkalast]

I've never looked at it this way, but it really is literally an underwater blimp lol.