Some diver use nitrogen to stay underwater for longer but usually compressed air is usedfor those who don't use nitrogen
Divers use 21% Oxygen and 79% nitrogen while underwater. It results in the same exact air we breath on the surface.
In a tenths situation is when sky divers use decimals.
The use of an oxygen analyzer would be advised. Most nitrox and technical divers have one.
Nitrogen
Any inert gas you are breathing.
In recreational diving, most divers use compressed air (as in the normal air we breather at the surface). Some divers are also trained to use special gas mixes called Nitrox which have a higher oxygen content and lower Nitrogen. Professional (or commerical) divers tend to use more advance mixes such as Heliox or Trimix which combine Oxygen, Nitrogen and Helium.
People who dive are usually just referred to as divers. You can break them up into roughly four categories:Skin divers - who hold their breath, and do not use scuba equipment. Also sometimes called free divers.Sport divers - who dive for fun (they used to be called 'recreational divers', but now this term is used to distinguish sport divers from 'technical divers' who also dive for fun, but dive outside of WRSTC 'recreational' limits).Commercial divers - who dive for their jobs. By convention, this excludes recreational diving instructors, to differentiate from commercial divers who use equipment underwater, engage in saturation diving and use of elaborate gas mixes.Military divers - who form a sub-set of the navy.Not all divers fit neatly into these categories (police divers, rescue divers, fisherman who dive for their catch), but those tend to be the broad categories used.
Many people use a SCUBA suit for diving. Sport divers, police divers and some Navy recovery divers.
Shamwow!
To use it in that form, you could use it as a command. For instance, Dive into the water. To use it in another way, you would have to change the verb tense to "dove" or "diving" or something else like that.
they need protection from stuff
The army of which country?