Divernet

The snorkel gets its name from a device carried during World War Two by U-boats, allowing them to remain submerged for long periods by taking on air through a specially designed tube.
But breathing tubes have their own history. They were first mentioned in the 4th century BC in the works of Aristotle, the Father of Zoology. He made many observations of marine life:
Just then as divers are sometimes provided with instruments for respiration, through which they can draw air from above the water, and thus remain for a long time under the sea, so also have elephants been furnished by nature with their lengthened nostril; and, whenever they traverse by water, they lift this up above the surface. The idea of snorkelling elephants was possibly based on information sent back to Aristotle by his former pupil Alexander the Great, during his campaigns and conquests of territory as far away as northern India. In ancient times breathing tubes were almost certainly hollow reeds and the like, as used for centuries in Ceylon and by Australian Aborigines to allow a silent underwater approach when hunting unsuspecting wildfowl. This method of hunting must have taken a lot of patience and also been quite difficult to carry out, because a straight tube would force the diver continually to look upwards, while gripping his nose shut. If there was a technical revolution in breathing-tube design, it was the introduction of the curve that allowed the diver to look forwards or downwards while on the surface, with or without a mask or goggles. The full curve did not arrive overnight. Our first hint of an ornate, or curved, horn being used as a breathing tube came from China around 320AD, in instructions from Pao Plw Tzu:
Take a real rhinoceros horn more than a foot long and carve on it the shape of a fish, then put one end in your mouth and enter the water - the water will open out three feet on all sides and you will be able to breathe out underwater.
Breathing tubes appeared attached to helmets in the European war books and treatises of the early 15th century. However, one doubts if these really worked well, as they were flexible and subject to collapse by water pressure.
It is only in the notebooks of Leonardo da Vinci that design improvements begin to appear. The tubes he illustrated had full bends, and most were reinforced against water pressure. Judging from one of his notes, these designs might have been based on information from far afield, as this observation from 1488/9 indicates:
This instrument is employed in the Indian Ocean in pearl fishing. It is made of leather with many rings so that these cannot close it up. Up above, the companion awaits in the boat while he (the diver) pulls out pearls and corals; he has goggles of frosted glass and a cuirass with large spikes in front... Although plenty of breathing tubes of one type or another were proposed in the centuries that followed, it was only in the late 1930s that the personalised type familiar to present-day divers found its place among e spearfishermen of the South of France.
A number of designs were patented, mostly made of aluminium, the lightweight properties of which were then finding many commercial applications. All had a small bore and, as pure aluminium was very soft, the trademark of an experienced diver during the 1950s was often a bent and battered snorkel hanging from his neck by a length of string. Snorkels were a necessity in this era of low-pressure cylinders, and a limited air supply that had to be used very efficiently. Safety boats were few and far between and usually rowed, as outboards were practically unheard of.
This often left divers to enter the water from a beach, snorkel a long distance to their dive site, make their dive then snorkel home again. In their way, these snorkellers were just as adventurous as modern divers, especially those few unwitting individuals who invested in a design with a double bend, the upper part including a small rubber cage that held a ping-pong ball.
The idea was that the ball would seal off the tube and stop water entering it while snorkelling. Those daring snorkellers who ventured deep found that the balls had a habit of imploding at around 40m. The loud bang was said to be a much better indicator of depth than the inaccurate gauges most people could afford!