Humans have always longed to explore underwater, but the need to breathe air has been an obstacle. From as far back as the 4th century B.C.E., clever inventors have been designing technology to give us face time with the creatures of the sea.
A depiction of Alexander the Great's 4th-century diving bell being lowered from a small boat into a fish-infested sea. This illustration is from "Romance of Alexander" a manuscript written and illuminated in Flanders, c.1340. (Photo by Hulton Archive/Getty Images)