Divers Are Buoyant
Scuba divers have an extra source of buoyancy that more than makes up for the weight of their gear: their wetsuits. Scuba cylinders, which seem heavy, lack the wherewithal to make up for the wetsuit because of their low negative buoyancy.
The science of buoyancy tells us that an object with a lesser overall density than water will float. For example, most forms of wood float because of the air trapped in the fibers and resins of the wood, making it less dense than water.
Wetsuits are made of neoprene, which traps a lot of air in microbubbles in much the same way that wood does. The result is that wetsuits are a source of net buoyancy for scuba divers.
Snorkelers and Wetsuits
Wetsuits are so buoyant that snorkelers wearing thick wet suits to cope with cold waters often find they need to wear light weights just to be able to make skin dives.
While compressed air is denser than air at standard atmospheric pressure, it is still not as dense as water. Scuba cylinders will not float on their own because of the metal, but their negative buoyancy is very low and not enough to overcome the positive buoyancy of the wetsuit.
A scuba diver needs to wear weights--and a lot of them--to be able to stay under water. A 5-foot-11-inch man who weighs 180 pounds will need to wear between 15.25 and 22 pounds of weights, depending on how thick his wetsuit is.
Article Written By Edwin Thomas
Edwin Thomas has been writing since 1997. His work has appeared in various online publications, including The Black Table, Proboxing-Fans and others. A travel blogger, editor and writer, Thomas has traveled from Argentina to Vietnam in pursuit of stories. He holds a Master of Arts in international affairs from American University.