Underwater diving equipment

Helium (from ) is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements, and it does not have a melting point at standard pressures. It is the second-lightest and second-most abundant element in the observable universe, after hydrogen. It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and

device used for breathing air from above when the wearer's head is face downwards in water

form of respiration in which a normally air-breathing organism breathes an oxygen-rich liquid (such as a perfluorocarbon), rather than breathing air

equipment used by underwater divers to make diving activities possible

diving equipment

light used underwater by a diver