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A canister style dive light. Night diving is underwater diving done during the hours of darkness. It frequently refers specifically to recreational diving which takes place in darkness. The diver can experience a different underwater environment at night, because many marine animals are nocturnal. [1]
Assess stability of underwater structures and avoid entry if a structure is unstable. Inhalation of salt spray Salt water aspiration syndrome: a reaction to salt in the lungs. Inhaling a mist of sea water from a faulty demand valve. Appropriate maintenance and servicing of equipment. [18] Inspect external condition and test function before use.
In such diving, light levels are often very low and the water is usually very turbid, so divers may rely on touch to guide them and to do their work, and they are connected via the umbilical to the surface. The umbilical serves as a supply of breathing gas, for communications, and as a lifeline to find and retrieve the diver in an emergency.
Divers must avoid injuries caused by changes in pressure. The weight of the water column above the diver causes an increase in pressure in proportion to depth, in the same way that the weight of the column of atmospheric air above the surface causes a pressure of 101.3 kPa (14.7 pounds-force per square inch) at sea level.
Water attenuates light by absorption, so use of a dive light will improve a diver's underwater vision at depth. [1] As the depth increases, more light is absorbed by the water. Color absorption depends on the purity of the water - pure water is most transparent to blue frequencies, but impurities may reduce this significantly.
Ocean optics is the study of how light interacts with water and the materials in water. Although research often focuses on the sea, the field broadly includes rivers, lakes, inland waters, coastal waters, and large ocean basins. How light acts in water is critical to how ecosystems function underwater.
The Ocean Photographer of the Year awards announced the winners of its 2024 contest featuring stunning images of underwater wildlife. 12 award-winning underwater photos give rare glimpses beneath ...
Water clarity is a descriptive term for how deeply visible light penetrates through water. In addition to light penetration, the term water clarity is also often used to describe underwater visibility. Water clarity is one way that humans measure water quality, along with oxygen concentration and the presence or absence of pollutants and algal ...