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How it works: Buoyancy Control Device (BCD)

A scuba diving buoyancy control device, or BCD, is a piece of diving equipment that allows a diver to easily adjust their buoyancy underwater. It is an essential piece of equipment for any scuba diver, as it helps the diver to maintain proper buoyancy while diving and allows them to move easily and comfortably through the water.

The BCD consists of a backpack-like harness that is worn by the diver, with a number of inflatable bladders attached to it. The bladders can be inflated or deflated using a valve on the BCD, which is controlled by the diver.

When the bladders are inflated, they add buoyancy to the diver, making them more buoyant and helping them to rise to the surface. When the bladders are deflated, the diver becomes less buoyant and sinks deeper into the water.

One of the main advantages of a BCD is that it allows the diver to adjust their buoyancy on the fly, without having to constantly add or release weight from their diving belt. This can be especially useful when diving in different environments or at different depths, as the diver can easily adjust their buoyancy to compensate for changes in water pressure and density.

In addition to the inflatable bladders, most BCDs also have a number of pockets or attachment points for carrying diving equipment, such as a diving knife, a torch, or a spare regulator. Some BCDs also have a built-in dive computer, which can be used to track the diver’s depth, dive time, and other important information.

Overall, a scuba BCD is a vital piece of equipment for any scuba diver, as it allows them to easily and accurately control their buoyancy while diving. Whether you’re a beginner or an experienced diver, a good BCD is an essential tool for safe and enjoyable diving.

Header image credits: Mitchel Wijt


Colin is Padi certified Divemaster, loves diving with the larger marine species around the world, and writing code.

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