All I ask of each reader is this, - Don´t die without having borrowed, stolen, purchased or made a helmet of sorts, to glimpse for yourself this new world. Books, aquaria and glass-bottomed boats are, to such an experience, only what a time-table is to an actual tour, or what a dried, dusty bit of coral in the what-not of the best parlor is to this unsupected realm of gorgeous life and color existing with us today on the self-same planet Earth.
William Beebe, Beneath tropic seas 1928
Beebe wrote this in 1928 - 15 years before the invention of the first doublehose reg. That´s why he mentiones “helmets”.