buoyancy

With how much lighter a step, with how much brighter an eye, did Francesca wander through the forest, even in the last desolation of autumn, than she did in all the bloom and buoyancy of spring!

Astronauts prepare for spacewalks by practicing their tasks underwater in a giant pool called NASA's Neutral Buoyancy Laboratory.

Many species of fish use an organ called the swim bladder, which is filled with gas, to adjust their buoyancy.

That won't impact the buoyancy?

The buoyancy, vivacity, energy, enthusiasm and ambition ordinarily associated with youth can be maintained through middle age and in some cases even to old age.

A body with negative buoyancy will sink in water.