Stories of humans diving into the depths of the sea have existed for thousands of years. Some are legends; others are true. Here are a few of the most famous tales:

• Gilgamesh (the Sumerian hero of the epic written in the ancient Akkadian language in the first half of the 3^rd Millennium B.C.) needed to find a plant that renewed youthfulness. He dove deep below the surface to find the plant.

• Scyllis (a Greek sailor) caused the Persian king (Xerxes I) great consternation when, breathing through a reed, Scyllis cut the mooring lines of the conquering King's battleships in the 5^th Century B.C.

• Alexander the Great used a diving bell (called the Colimpha) in 330 B.C. to penetrate the unseen, unknown, underwater world.

• Guglielmo di Lorena invented "a strange instrument" - the predecessor of the modern diving bell. It was "a wooden bell" reinforced with metal rings that would allow people to dive and work under water. (Scroll down about 25% on the link to read the story.)

• A 16^thCentury diving bell was used for salvage.

• Giovanni Borelli attempted to recycle his own breathing air in 1680. His device didn’t work, of course, since exhaled human air contains too much carbon dioxide.

• Sir Edmund Halley (after whom the famous comet is named) proposed two types of diving bells in 1716.

• During the American Revolutionary War, patriots planted explosives on British ships. The device they used was called "Bushnell’s Turtle." 

• In 1912, the "Tritonia," a "one atmosphere" dive suit was used to explore the wreck of the great ship Lusitania. 

Mother-of-pearl adornments exist at many ancient archeological sites. Divers would have had to retrieve the precious material from the ocean. Long before diving bells and sophisticated equipment were invented, men held their breath and dove below the surface. But something happens to a human body when the pressure of the sea acts on the air a person inhaled at the surface. It took centuries before that mysterious process was understood.