No science behind that but I like them to have just enough buyoancy to float barely. Entirely submerged but staying two inches underwater.
Quick! Do Gelatinous Cubes float?
Elijah James
Evan Sanders
The next villain of your setting is a wizard who finally found out how to make those cubes finally fly. The dragons are pretty upset that their airspace is full of flying shit and require small people to find the source and eliminate it.
If you want to crank it up a bit, the wizard used some stuff like Dust or Tiberium on the latest batch, who have become sentient and very, very creepy looking.
Hunter Cox
No, gelatinous cubes are denser than normal oozes, and virtually all acids are denser than water (or mix with water, so can't really say if they float or not)