The best replacement for buoyancy is density.

The best alternatives to buoyancy are rated as following:
★★★★★  density

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Speaking about buoyancy, one probably shouldn't forget about hot air balloons.

Other search terms related to buoyancy and their ratings are:
★★★★★ hot air balloons
★★★ wetsuit
You have in mind a companion for buoyancy and it is not yet here? Propose!



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buoyancy
density