Neutral buoyancy – what, why and how

A scuba diver’s ability to establish and maintain neutral buoyancy throughout the dive and with any equipment configuration is one of they key skills that any beginner diver should master. Being neutrally buoyant under water is what makes a diver feel confident, safe and gives him or her the opportunity to truly experience all the joys and beauty of the underwater world. Once neutral buoyancy becomes your second nature, your can take your scuba diving adventures to a whole new level.

What is buoyancy?

Every object placed in the water has a tendency to either sink or float. Objects that float are said to have positive buoyancy while those that sink – negative buoyancy. When objects float, it means they weigh less than an equal volume of water and when they sink – this means they weigh more. An object is neutrally buoyant when it neither sinks, nor floats. The first obvious thing that distinguishes an experienced diver from an inexperienced one is their ability to achieve neutral buoyancy and remain suspended at a particular depth without effort and without using their limbs (neither arms, nor legs).

Why neutral buoyancy?

At the beginning of the dive, a diver needs to establish negative buoyancy in order to descend to the planned depth; positive buoyancy is needed to ascend. Neutral buoyancy means that a diver can remain suspended at a particular depth for a period of time (planned depth, safety stop at 5 metres for 3-5 minutes, etc.), neither floating nor sinking. This makes for an effort-free, enjoyable dive, ensures that a diver does not overexert him- or herself by trying to stay off the bottom, does not descend too deep or ascend too fast. It also plays a role in protecting the marine environment from damage, such as broken corals, inflicted by divers who cannot stay neutrally buoyant. For example, many scuba diving facilities, especially the ones located in areas with abundant marine life or archeological sites, may well refuse to accept divers who cannot maintain neutral buoyancy.

How can you achieve neutral buoyancy?

Neutral buoyancy is achieved by means of proper weighting. Deflating and inflating your BCD (Buoyancy Control Device) and adjusting your breathing pattern throughout the duration of the dive are also necessary to control your rate of descent, ascent, and to help you establish neutral buoyancy at a particular depth. In addition, practice makes perfect. For experienced and well trained divers achieving neutral buoyancy becomes second nature.

Proper weighting

Neutral Buoyancy - Open Water Diver TrainingYou may have noticed that all divers wear either a classic weight belt or weights integrated into their BCD. Scuba equipment that a diver is wearing (scuba unit, exposure suit, etc.), water salinity level (fresh or salt water), and a number of other factors determine how much extra weight a diver needs to wear. To test whether a diver is properly weighted, he or she needs to enter shallow water, wearing all their gear, deflate their BCD completely and see if they can float just above their eye level with each inhalation and sink just below the surface with each exhalation. If they can, this means they are correctly weighted. With experience, you will know how much weight you need, depending on circumstances.

Your BCD and your lungs

Having proper weights, however, is not enough to ensure that you remain neutrally buoyant underwater. On descent, air in your BCD compresses under pressure, on ascent – it expands as pressure decreases on your way to the surface. To control your rate of descent and ascent and to remain neutrally buoyant at depth you also need to make use of your BCD and your lungs. By releasing air from your BCD or adding air to it, you can adjust your buoyancy. In addition, you can and should use your lungs as your primary buoyancy device by inhaling or exhaling air. Experienced divers rarely use their BCD’s inflator / deflator – this, however, comes with training and practice.

Courses you can takeSSI Perfect Buoyancy Course

The Open Water Diver Course includes many exercises to practice controlling your buoyancy. In addition, a specialty course called Perfect Buoyancy is available that focuses entirely on mastering this important skill. Once you learn how to achieve neutral buoyancy, you will never look at scuba diving the same way again. Neutral buoyancy gives you the opportunity to experience a feeling of weightlessness, not unlike what astronauts experience in space. This feeling is unforgettable and you do not need to reach up to the sky to experience it!

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