After instruction on shore, the pair take us out to sea, to learn buoyancy control, mask clearing and buddy breathing.

Photography, buoyancy control, fish identification and the exploration of wrecks are also part of the course.

Boat skippers often throw anchors on to reefs rather than use set moorings, and divers with bad buoyancy control can easily break the delicate structures.

These include equalizing, buoyancy control, inversion recovery, emergency venting and blowup recovery.

These two methods, need special precautions in buoyancy control.

The container trapped hydrogen and floated, with a crude spring valve to maintain buoyancy to keep it at a constant depth.

Many fish maintain buoyancy with swim bladders.

For example, larger floats may be used with liquids with specific gravities as low as 0.5 while still maintaining buoyancy.

Successful growth and division for algae relies on a balance between maintaining buoyancy in the euphotic zone (which contains ideal light and nutritional conditions) and avoidance of grazing predators.

We also went diving in a deep pool, because that helps you get used to the feel of neutral buoyancy that you get in space.

Later work on buoyancy showed that many deep-sea dogfish sharks achieved neutral buoyancy by storing especially light oil in their enormous livers, as do basking sharks.

Deep sea stingrays are benthopelagic, and like the squaloids have very large livers which give them neutral buoyancy.

Submarines in a neutral buoyancy condition are not intrinsically trim-stable.

It operates close to neutral buoyancy and doesn't require a winch.

In turn, the additional investment will provide buoyancy to the price, thus completing a positive feedback loop.

There are pneumatocysts at intervals along the fronds which provide buoyancy.

They are 310ft m long, 50ft m wide, and 17ft m tall, and contain 21 water-tight air-filled cells with leak detectors to provide buoyancy.

Like the fin and tailplane, the wing was a fabric covered wooden structure, but one subdivided into sealed cells to provide buoyancy in case of hull flooding.

Large oil or gas drums were cleaned and filled with medical supplies and food, with enough air space to provide buoyancy, and strung together with rope.