Good trim is horizontal although, when not used to it, perceptually one feels a bit head down and it requires practice in order to feel natural.

When we achieve good trim we achieve additional comfort, in addition to reduced risk of entanglement/damage to fragile environments and reductions in visibility from disturbing silty bottom conditions whilst fining.

Divers initially struggle with proper trim, and seek equipment remedies to trim issues (such as ankle weights) which are a poor substitute for proper technique and can lead to greater problems. Trim should not require tail weights, moving bands, longer cylinders, or any other fancy arrangement of kit. A diver should be able to position themselves, by shifting tank and weight system height, into a perfectly horizontal hover. This can be tested by a diver seeing if they can view everything that is going on behind them simply by tucking their chins to their chests.

To achieve good trim, arch your back with head and knees upward, keeping your feet flat in the same orientation to your ankle as when standing up (horizontal to the bottom) a position which assists stability. Push your head back so that you can see ahead of you, and use your arms and legs to adjust your position to get comfortable and stable in the water.

The recommendation of the use of arms and legs as counterweights around the centre of gravity should not be seen to suggest that that the use of hand movement should play any part in stability. Divers often incorrectly imagine that hand movement can stabilize them in the water; and with reinforcement through repetition this action often becomes subconscious, disturbing sediments, efficiency of movement, gas consumption, and diving proficiency. In truth, hand movement is an extremely inefficient action, creating a range of diving problems. Many divers presented with silty conditions commonly ruin visibility with erratic hand movements. Advanced divers, and particularly those in technical diving, must eliminate these movements completely to achieve stability in the water.

Certain buoyancy control devices can actually complicate the problem of proper trim. For example, BC’s with restrictive bungies can promote gas trapping and increase drag by generating turbulent flow around the diver and trapped gas pockets can imbalance the diver with unequal pockets of lift. The familiar traditional jacket style of buoyancy compensators is designed to lift the upper portion of the torso, making it even more difficult to remain horizontal whilst under the water. With practice it is possible that a diver may be able to adjust body position to overcome this natural design fault but back mounted buoyancy compensators help us achieve proper trim, allowing greater comfort and stability in the water.