Buoyancy, Buoyant

Buoyant or buoyancy is relative to the sinking or floating characteristics of an object in liquids. We can say objects are positively buoyant or have a positive buoyancy when they float. Inversely are negatively buoyant when they sink, and neutrally buoyant when they neither float or sink and remains at the same depth.


Normoxic is the name given to a breathing gas mix for which the percentage or fraction of oxygen is similar to the one of air, but contain a different mix of other gases. Along with hypoxic and hyperoxic, normoxic is one of the three kinds of breathing gas mixes for diving.


Hyperoxic is a term used for breathing gases that has a higher percentage or fraction of oxygen than regular air. The term or word is not so commonly used because of the designation Nitrox or Enriched Air, which is used instead to cover hyperoxic gases. It is the opposite of hypoxic.

WOB – work of breathing

The work of breathing or WOB is in simple terms, the effort required by the lungs to breathe. But to be more accurate it refers to the energy expended to inhale and exhale a breathing gas. The WOB is usually expressed as work per unit volume.


The process known as “upwelling” is caused by the winds blowing across the surface of the ocean and push water away. Colder water then rises up from deeper beneath the surface to take the place of the water that was pushed away. It is also the opposite of downwelling.

Quick release

A quick release is a form of clip used for diving equipment. It is usually associated with a weight system but applies to many other purposes such as the releases of shoulder straps.


A rattle in diving is a piece of equipment designed to get attention by making a rattling sound. It is usually a hollowed tube with both ends plugged and containing metal balls. Shaking it create a sound from the shock of the balls.

Octopus – Octo (gear)

The Octopus or Octo is another name to designate the alternate air source on a diver regulator set. It comes from the first brand to introduce it Aqualung and named it Octopus. They also introduced the bright yellow color that almost all alternate regulator now has.

lb – lbs

lb or lbs are the short unit designation for pounds. It is a measurement of weight coming from the imperial system of units. One pound is equal to exactly 0.453592 kilograms.