The first divers to use any type of diving apparatus were probably breathhold, or free divers. An Assyrian artifact from about 900 B.C. is among the earliest records of free diving gear. A frescoe depicts a swimmer breathing underwater from a goat skin. By the 5th century B.C. Greek divers used breathing tubes while in the water. The earliest record of swimming goggles is from a second century A.D. vase of Peruvian origin. Tortoiseshell goggles and breathing tubes were routinely used by free divers by the Middle Ages.

The diving bell, another early device that allowed man to descend and observe the underwater environment, is open to the water at the bottom. From its earliest use, this allowed divers to go on short forays out into the open water and return to the bell for air. However, the air inside would quickly become stale...