The buoyancy cycle

The buoyancy cycle - techniques to achieving a good balance

David Mansfield1 comment

When discussing buoyancy control, divers are actually talking about two critical skills. The first is the act of hovering and the second is the coveted "trim" we often hear from experienced bubble blowers. Both of these techniques are essential in achieving excellent buoyancy control. 

Divers want to stay off the bottom. The act of achieving a hover helps accomplish this for a number of reasons. Divers do not want to damage the ocean any further than it is currently impacted by human interaction. A fin kick to a 200-year old piece of coral or the crashing of a human body into a beautiful gorgonian can create a ripple effect that destroys much more than the initial impact. Additionally, when a diver is in the water column and in a comfortable hover position, they are at their most relaxed. A comfortably chill diver will save a ton of air by maintaining perfect control on their dive. Most divers will notice this as they dive more often. Their first dives will be 20-30 minutes and slowly, they'll experience that the same tank is providing them with more time underwater. This is because they are relaxed and capable of smoothly moving through the water column. 

How do we achieve neutral buoyancy? It's actually quite simple. A diver who achieves neutral buoyancy correctly will not require much movement to move around underwater. There are numerous methods to check our weighting first. Having the correct amount of weight (and correct placement) will spell success to a diver. In the Open Water course, we learn that our body will displace water equal or greater to the amount of water that it sits in. Which is why most people float. We counteract this resistance by adding weight to our equipment. This weight coupled with a buoyancy control device (BCD) will guarantee success in the water. A diver can sit at the surface of the water and conduct a buoyancy check. This helps determine the correct amount of weight. With the regulator in the mouth, the diver can empty the BCD fully. As you begin to sink, take a full breath of air into the lungs. The diver should settle at the water line where their mask is located. If the diver does not move further down, it means that they do not have enough weight on their body. If the diver sinks to the bottom like a rock, that means that they have too much weight on. Why does that matter? 

Diver with neutral buoyancy

Too much weight will turn a relaxing dive into a workout. As the diver is dealing with the adding resistance, they will find themselves breathing harder and losing the ability to be underwater for a longer period of time due to air consumption. If the diver does not have enough weight on, they will not be able to sink. If the diver can get below the waves, they will have trouble staying down. Which means more swimming, more get the point. 

Now that we've determined that we have the correct amount of weight on our bodies, we can descend. There are two methods of achieving neutral buoyancy underwater. The first was previously known as the fin pivot. This was a check underwater to start the dive. The intent was that the diver could control their buoyancy through the act of breathing. As our training organizations have advanced their skills, we now do this skill from a neutrally buoyant position and display it by slowly breathing in and out to show that we are controlling our vertical position in the water column by breathing in and out. Instructors used to say that it was like doing push-ups without arms. The diver was able to effectively control their buoyancy and the hope was that divers would realize that they did not need to use their BCD for every single adjustment on a dive. For example, maybe the diver is cruising along and encounters a large rock. A neutrally buoyant diver can breath in slightly and make the body rise. As the diver goes over the rock, they let that air capacity out of their lungs and slowly descend into the original position. 

The pinnacle of buoyancy control is the actual act of hovering. Hovering reveals certain things about the diver. First, it is lung control. When hovering, a diver is not breathing heavily in and out. Doing so, will make a neutrally buoyant diver shift the vertical position drastically. A diver who can control this will settle in the water and maintain position. It is also a challenge to actual movement. Divers who are swinging their arms or constantly moving their legs will not achieve a proper hover. The diver should be able to sit comfortably in position without movement. This displays that buoyancy control is achieved. A hovering diver will also reveal the second part of a successful skill, which is trim control. 

Diver hovering

If a diver is falling backwards, sitting on their side, canted to one side, etc.; they reveal that the weighting is incorrectly positioned. It does not sound like a big deal for a diver to deal with off kilter weights, but it is. If there's too much weight on one side versus the other, the diver will have to compensate that effort through muscle engagement. Though we are in a weightless environment, we are still able to use muscles to maintain balance. Imagine doing an hour of planks underwater. This expends energy and results in a diver who is wasting air because they are too busy trying to maintain a balance in the water. This can be overcome through a proper hover scenario in a pool. The diver can make weight changes by shifting weights, moving them to different positions on the body or by using video recordings to see how the body is performing while diving. 

Once the diver has achieved proper weighting, proper buoyancy and proper trim, they can begin work on the final skill. This is known as streamlining. 

Streamlining is the conscious act of ensuring hoses, materials, swimming position and kicking of the fins are as efficient as possible. The low pressure inflator hose, the submersible pressure gauge and the regulators should be streamlined to the body. A dangling SPG, for example, can create drag or possibly become an entanglement hazard. By tucking this item in to an area of the body that it can be accessed easily, but also not create drag will ensure a more efficient diver. The diver who is neutrally buoyant will not be on the ground, they will be a few feet above and enjoying the weightlessness that all divers love. Finally, the efficient fin kick will then complete the perfect diver. By generating the power from the hips and keeping the knees as engaged as possible, a diver will glide through the resistance of water and not be tired at all while moving quickly through the water.   

Properly trimmed diver

A diver who is neutrally buoyant and properly trimmed will result in relaxation. From there, they can work on gliding through the water slowly and surely with those beautiful fins on their feet. Divers will then experience longer dives and find themselves enjoying the dive much more because they aren't associating a dive with work.

With these techniques, you can begin working on achieving neutral buoyancy and body positioning that will ensure your success. If you are interested in learning more about this act, it is a great idea to sign up for the Peak Performance Buoyancy program. This is a fun course that challenges divers to work on the skills that will result in superior buoyancy control. After a pool session, the diver will go out to accomplish two dives in the ocean where they will continue to hone their capabilities as a diver.

Get out there and dive today!

About the Author:
D.J. Mansfield

D.J. Mansfield is a PADI Course Director who dives Southern California and has done so for 24 years. He is currently the Director of Operations for Beach Cities Scuba and is a committed ocean steward and trainer for divers all over the world. 

Follow him on Instagram @djmansfield7 or contact him at   

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1 comment

Steve Schroeder
Steve Schroeder
Thank you for this, as a newer diver, buoyancy and the corresponding overuse of air is a challenge. I have much to work on and much to learn. I currently use 2kilos of weight in each pocket of my Cressi BCD. Would there be value of trying weights in the back pockets? My body is dense. As a highly trained swimmer, I do not naturally float. While diving, I have practiced taking deep breaths to ascend a little swimming over coral and other objects.

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