The amphibian survival mask is part of a trifecta of items needed for a non-aquatic species to survive in an aquatic environment. While the aesthetics may differ, the mask functions at its most basic level, to provide a sealed air space with a clear window in front of a sentient’s face where air can be pumped in to facilitate the non-optional activity of breathing. The enclosed air space also allows the wearer’s eyes to focus underwater, as most terrestrial sentients do not possess eyes that can focus clearly underwater, resulting in blurred vision if they dive without a mask.
Basic models of the mask are little more than flexible hoods attached to a clear polymer or glass shield that seals to the face with a collar of soft, waterproof material. These models accommodate respiration and vision, but little else. They can be subject to fogging and may require periodic clearing underwater. More expensive models might include a more rigid helmet that protects the cranium from impact, as well as a mask that incorporates not just a regulator to ensure smooth flow of air, but basic communication equipment to enable the diver to talk with his fellow divers. More sophisticated masks can incorporate built-in illuminators, integrated life support displays, even targeting arrays and the like. Truly, what a mask of this type can be fitted for is limited solely by the budget of the buyer and the limits of comfort.
Apart from the physiology of the diver and the cost, another factor that governs the form of the amphibian survival mask is its intended use. With pressure increasing the deeper one dives, masks intended for deeper diving need to be of stouter construction than those intended for recreational purposes. While a mask intended for shallow water and hobby diving, those intended for deep-sea hazardous occupations typically feature a rigid body of durasteel or some similar high tensile metal to withstand the crushing pressure at depth, with a small vision panel made of thick tempered glass or clear polycarbonate material.