Buoyancy tersely: Buoyancy = weight of displaced fluid. Archimedes' principle does not consider the surface tension (capillarity) acting on the body, but this additional force modifies only the amount of fluid displaced and the spatial distribution of the displacement, so the principle that "Buoyancy = weight of displaced fluid" remains valid. The weight of the displaced fluid is directly proportional to the volume of the displaced fluid (if the surrounding fluid is of uniform density). In simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or
Buoyancy compensator (diving) uses the casing for load bearing purposes and to protect the bladder, which is a replaceable part. The diver needs to be able to establish three states of buoyancy at different stages of a dive: To achieve negative buoyancy, divers who carry or wear buoyant equipment must be weighted to counteract the buoyancy of both the diver and the equipment. When underwater, a diver often needs to be neutrally buoyant so that the diver neither sinks nor rises. A state of neutral buoyancy exists when the weight of water that the diver displaces equals the total weight of the diver.