On this planet of water, the natural elements of air, water and minerals cause certain effects which divers become aware of once they descend below the surface. Magnification is a result of refraction of light energy waves which can be seen if one would place a pencil in a glass of water. This is the result of these energy waves being bent as it passes from one medium to another.
Examples are sunlight entering the atmosphere being bent like a prism.
Where some are reflected and results in a blue sky. Then as these energy waves enter water, which is denser than air, the sunlight gets refracted again. Once reflected off a subject it then passes the glass of a mask and is bent again. Another way of saying this, objects that are four feet away, will appear three feet. For the photographer the way objects appear is the same as how distance is set on the lens.