Diving
In 1935, using a 1 atmosphere dive suit developed by J. Peress, divers explored the wreck of the Lusitania. Click image for larger view and more details.
How long can you hold your breath underwater? For a minute, maybe two? What do you see when you open your eyes underwater? What can you hear? How fast can you swim? When we venture into the water, none of our senses seem to work very well. We certainly can’t see or hear clearly, it's impossible to breathe, and as anyone knows who has been in the water too long, we get cold and may turn blue. We are creatures evolved to live on land. Unaided by technology, people are about as helpless underwater as, well, a fish on grass.
Due to these limits of our physiology, most of the oceanic world has remained unexplored. To our fragile bodies, the underwater realm is as alien and hostile as outer space. Despite these difficulties, the human spirit of exploration has driven us to figure out how to get into the water, observe its unknown expanses, and uncover the mysteries of the deep.
The invention of the "aqua lung" in the 1940’s (now commonly called scuba, which is an acronym for "self-contained underwater breathing apparatus") opened up the underwater realm to scientists, photographers, and recreational divers. Placing people into the marine environment, however, has always been a dangerous business. The effects of increased pressure on body cavities and the gases that dissolve in body tissues limit the depth and duration of underwater dives.
Although technological advances keep making it possible to dive deeper, severe restrictions remain on the depth and length of time that divers can spend underwater. Research in undersea ecosystems often requires diving to depths beyond 40 m (141 ft) -- depths that exceed the limits of conventional scuba equipment. Divers can extend their bottom time by breathing nitrox, a mixture of oxygen enriched air, but are still limited by weather, gas supply in their tanks, and the risk of decompression sickness commonly known as "the bends."
In this section, diving, we highlight some of the technical advances in diving and discuss some of the problems we still must overcome.
