Neutral buoyancy

In other words, an inflatable boat that displaces 100 pounds (45 kilograms) of water is supported by the same amount of force.

Ways to adjust buoyancy were developed to produce equipment such as the inflatable life jacket, which is filled with gas and helps to reduce a person's average density, assisting in floating and swimming, as well as certain diving equipment (including submarines and submersibles) which have adjustable volume air chambers to regulate buoyancy.

Many swimmers know that there are easy ways to float at the surface, such as lying on one's back or holding a full breath.

Neutral buoyancy is used extensively in training astronauts in preparation for working in the microgravity environment of space.

When a fish's overall density becomes higher or lower than the surrounding water due to volume change of the swim bladder following ascent or descent, it can correct this difference over time by a physiological process involving controlled absorption and elimination of gases via the blood circulation, the gills, and a gland adjacent to the swim bladder.

The human brain exhibits approximately neutral buoyancy as a result of its suspension in cerebrospinal fluid.