What about being able to make balloons like Zero 2 infinity?
What about floating bases in dense atmospheres?
Buoyancy now works for the water, but making it work with fluid density can make the game much more interesting, with the "water" on different planets having different densities and not adding 2 different systems for buoyancy and some crafts floating on some atmospheres using the code we already have.
A new fuel called Helium or a new part for floaters would be very entertaining.
I would love to see this