The two controls
- Your BCD sets your broad buoyancy — add small amounts of air as you descend, vent as you ascend
- Your breath fine-tunes it — a fuller breath lifts you slightly, exhaling drops you
Get weighted right
Over-weighting is the most common cause of poor buoyancy and high gas use. Do a weight check: with an almost-empty tank, you should float at eye level holding a normal breath and sink slowly as you exhale.
Aim for a horizontal, relaxed trim. Good buoyancy keeps you off the reef and lowers your SAC — measure yours with the SAC estimator.