Only after attending to proper weight­ing and trim can you expect to achieve consistent control over your buoyancy. Given a typical profile of descending to a certain depth and remaining at or near- that depth for the majority of the dive, the ideal is to establish neutral buoyancy by adding air to the BC, if necessary, and then not touching the inflator again until you are ready to surface.

Minor variations in depth are accom­plished by using the lungs to alter buoy­ancy — breathing slightly more deeply to swim over an object and exhaling more deeply to sink hack down. Larger changes in direction and body position are handled primarily by the fins. After awhile this technique becomes second nature, however, specific exercises can help develop this skill most effectively.

A simple exercise used for testing your weighting, the fin pivot, is also valuable to increase awareness of the ef­fects breathing has on buoyancy. To work best, the fin pivot should be per­formed in a pool or confined water that is not subject to water movement.

Lie facedown on the bottom with no air in your BC. Add air with short spurts of your power inflator until your upper body just begins to rise but your fins remain on the bottom. From this neutral buoyancy position inhale and exhale more deeply than normal. Notice how far your body pivots up and down.

Pay particular attention to the de­layed reaction between breathing and body movement. When applied, this knowledge can make all the difference between bumping into an underwater feature and gently gliding over it.

Aside from understanding, the role of breathing in mastering buoyancy skills, another crucial aspect is to reduce body movements to a minimum. With proper weighting and trim it is possible to maintain a horizontal body position without using the hands or kicking. Practice minimal body movement by hovering. Try to remain at a constant depth for several minutes without mov­ing. At a given depth, fold your arms across your chest, cross your ankles and gradually add air to your BC until you become neutral. Your depth should vary only slightly with each breath: be prepared to compensate by breathing shallower or deeper if you begin to float up or sink.

Practice hovering horizontally and vertically. The ultimate test of your hov­ering ability is the “Buddha” position — legs crossed in a sitting position, hands grasping the tips of the fins. If you can sustain this hover without turn­ing over forward or backward, you’ll know that not only do you have good buoyancy skills, but also your weighting and trim are well-adjusted.

A final test of buoyancy skills is to suc­cessfully maneuver a buoyancy practice course. These consist of a series of geo­metric shapes, such as a diamond and a circle, made of PVC pipe. Typically they are anchored above the bottom at various depths. The objective is to swim through each shape without touching the frame. Perfecting buoyancy control is largely a matter of repetitive practice. But you can he certain of using- the proper techniques and practicing in a safe environment by enrolling in a buoyancy specialty class.