What is Buoyancy: The formula

neutral buoyancy diver

Post by DPM Diving

July 2, 2021

Mastering perfect buoyancy should be every new diver’s number one priority.

Moving underwater naturally not only makes your dives more enjoyable but also safer.

Let’s see why and how to do it!

Benefits of Perfect Buoyancy

Having perfect buoyancy improves your air consumption allowing you to make longer dives, increases your safety by preventing diving accidents, and prevents you from making movements that may disturb the underwater ecosystem

perfect buoyancy
Our Instructor Trainer Mery diving in Gili T., Indonesia

Buoyancy formula: How to Achieve it?

Perfect buoyancy is the result of having the right ballast, adopting a hydrodynamic body position, performing the correct finning, and having an efficient and safe breathing rhythm.

For those just beginning to venture into diving, this mastery is achieved with training and practice.

Once you understand how to achieve that balance, moving underwater naturally becomes a habit.

diver with perfect buoyancy
Our Instructor Nico diving in Koh Tao, Thailand.

Buoyancy Control System Components

To refresh your memory a bit, the buoyancy control system is what allows us to control our ascents, descents, moving underwater and floating on the surface.

It is composed of the buoyancy compensation device (BCD) and the weight system (in integrated pockets or on a belt).

There are other components of the diving equipment that also influence buoyancy but are not part of this system.

The suit, the fins, the scuba tank, even our physical build will have an impact on our buoyancy. 

scubapro bcd
Buoyancy Control Device (BCD) – Check out more at our Online Shop.

Types of Buoyancy

In diving terms, buoyancy can be:

  • Positive
  • Negative
  • Neutral

We achieve positive buoyancy whenever we float or feel a force propelling us to the surface.

Negative buoyancy is the buoyancy we feel when there is a force sinking or pushing us down.

Neutral buoyancy is the balance between these forces, when we move along the same water line in the same direction, neither floating nor sinking. 

To achieve perfect buoyancy, we must master these 3 types of buoyancy throughout the dive and understand when we need each one, and to know how to achieve them.

Positive Buoyancy

Whenever we are on the surface of the water before we start our dive and once it is finished, we must make sure that we can float comfortably and effortlessly.  

To achieve this goal, it is necessary to inflate our buoyancy device (BCD) to its maximum capacity.

If the BCD is the right size and works properly, and we are not over-ballasted, we will be able to stay on the surface without any problems. 

Remember that if necessary, you can get rid of your weight system to achieve positive buoyancy.

Getting rid of your ballast is not a common practice but it is an action to consider in case of a malfunction of our BCD or in an emergency situation

positive buoyancy scaled 1 - What is Buoyancy: The formula
Diver floating in the surface. Check out our Instagram for more diving content.

Negative Buoyancy

When making a descent, either by line or with a visual reference, we will need to achieve negative buoyancy.

We will achieve this by releasing the air from our BCD little by little and accompanying it with body posture and breathing

A controlled descent is achieved by removing the air from our buoyancy device, gently flapping to control the rate of descent (to compensate our ears), and breathing normally. 

If, when attempting to descend in a vertical fin-first position (fins down-head up), finning fast and continuously, we will remain at the surface and tire ourselves out.

On the other hand, if we breathe too deeply and exaggeratedly, the air in our lungs will prevent us from descending.

Negative bouyanct
Diver descending into the Blue Hole, Egypt. Check out our Instagram for more diving content.

Neutral Buoyancy

Neutral buoyancy is that sensation of feeling that we are flying underwater.

It is the buoyancy we need to move underwater and to control our ascents (another important fact to refresh: ascent speed should not exceed 9 meters per minute).

neutral buoyancy
Our Diving Instructor Barba diving in Gili T., Indonesia.

Mastering Perfect Buoyancy

Moving efficiently underwater allows us to enjoy our dives, prolong them, prevent accidents and preserve the underwater ecosystem.

To achieve this type of buoyancy, several elements must be taken into account:

  • The amount of ballast: it depends on the diver’s build, the type of wetsuit he/she is using, the type of water (fresh or s8.ea), the diving conditions, and sometimes the depth of the dive.
  • Body posture: to move in a natural way we must adopt a hydrodynamic posture, with a slight angle of inclination of our chest, so that when finning we move forward.
  • Breathing: it is essential that we are relaxed and that the breathing pattern is normal and balanced. The exhalation time should be at least as long as the inhalation time.

With the right training and practice, divers get to perfect technique, improve posture, make adjustments to their equipment and adapt to changes in the environment, mastering their neutral buoyancy.

Having control over displacement and ascent speed are indispensable skills for any safe and responsible diver.

It is not a challenge that is achieved overnight, but it is one that is very worthwhile!

moraynp - What is Buoyancy: The formula
Diving with Morays in Nusa Penida, Indonesia.

If you want to get into scuba diving, or if you are already a diver, stay tuned for our next articles where we will talk more about this topic.

Also, if you already have your certification and would like to reinforce your knowledge and improve your buoyancy skills we invite you to participate in the Perfect Buoyancy Specialty program.

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  1. Avatar

    Great article! Thanks for sharing this valuable tips. Will definitely practice to improve my buoyancy skills

    • Avatar

      Hi Jules, thanks for your comment. We are glad to know you enjoyed it 😉
      The best way to improve your buoyancy skills is to take the Perfect Buoyancy course and then practice, you’ll note improvements in the very next dives 🙂
      Let us know if you need any personalized tips, you can reach out by WhatsApp or through the contact page.

  2. Avatar

    there’s a course to improve buoyancy?? can you send me details please?

    • Avatar

      Hi Alvaro, actually yes! There’s a Specialty course called Perfect Buoyancy, and there’s also the Perfect Buoyancy adventure, which is part of the Advanced Adventurer course. We’ll send you details by email 😉


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