Neutral Buoyancy

The state in which a diver neither sinks nor rises, weightless in midwater, achieved by exactly balancing weight against displacement.

Neutral buoyancy is the state where the downward pull of your weight exactly matches the upward push of the water you displace, so you neither sink nor float. A neutrally buoyant diver hangs weightless in midwater, moving up or down a little with each breath, an inhale adds displacement and lifts you slightly, an exhale lets you settle. It is the closest most humans get to flying, and it is the baseline condition for almost everything else in diving.

Neutral is not a set-and-forget state, because the balance shifts throughout the dive. Descend and your exposure suit compresses, making you negative; breathe down a tank and you lose roughly 2 kg or more of gas weight, drifting positive toward the end of the dive. Staying neutral therefore means small ongoing corrections with the BCD and constant fine control with the lungs. The proof skills are the hover, holding position without sculling or finning, and an unhurried, stable safety stop at 5 m.

Training courses formalize it early, fin pivots and hovers in open water class, and refine it forever after. The enabling condition is correct weighting: an overweighted diver needs a large air bubble in the BCD that expands and contracts violently with depth, making neutral a moving target. Get the weight check right and neutral buoyancy stops being a fight and becomes something close to easy.