|4500BC - Coastal cultures such as those found in Greece, Mesopotamia, China, and probably many other parts of the world, engage in diving as a form of food-gathering, commerce, or warfare.
1194 - 1184BC - Divers are involved in military operations during the Trojan Wars. They sabotage enemy ships by boring holes in the hulls or cutting the anchor ropes. Divers are also used to construct underwater defenses designed to protect ports from the attacking fleets.
1000BC - The writings of Homer mention Greek sponge fishermen who plummet to depths of almost 30 meters (100 feet) by holding a heavy rock. They knew little about the physical dangers of diving. To try and compensate for the increasing pressure on their ears, they poured oil into their ear canals and took a mouthful before descent. Once on the bottom, they spit out the oil, cut as many sponges free from the bottom as their breath would allow, and were then hauled back to the surface by a tether.
500BC - A Greek diver named Scyllias and his daughter Cyana use diving reeds to cut the mooring lines of the Persian King Xerxes fleet.
414BC - The first account of diving used in warfare is found in the narration of the siege of Syracuse by the Greeks, written by the historian Thucydides. He tells of Greek divers who submerged to remove underwater obstacles from the harbor in order to ensure the safety of their ships.
360BC - Aristotle mentions the use of a sort of air-supply diving bell in his Problemata: "...in order that these fishers of sponges may be supplied with a facility of respiration, a kettle is let down to them, not filled with water, but with air, which constantly assists the submerged man; it is forcibly kept upright in its descent, in order that it may be sent down at an equal level all around, to prevent the air from escaping and the water from entering...."
332BC - Alexander the Great, in his famous siege of Tyre (Lebanon), uses demolition divers to remove underwater obstacles from the harbor. It is reported that Alexander himself made several dives in a crude bell to observe the work in progress.
100BC - Salvage diving operations around the major shipping ports of the eastern Mediterranean are so well organized that a scale of payment for salvage work is established by law, acknowledging the fact that effort and risk increase with depth.
77 - Plinius the Elder mentions the use of air hoses by divers.
200 - Peruvian vase shows diver wearing goggles and holding fish.
1300 - Persian divers were using underwater eye-goggles, made from
the polished shells or tortoises
1500s: Leonardo da Vinci designs the first known scuba. His drawings of a self-contained underwater breathing apparatus appear in his Codex Atlanticus. Da Vinci's design combines air supply and buoyancy control in a single system, and foreshadows later diving suits. There is no evidence that he ever built his device. He seems, instead, to have abandoned scuba in favor of refining the diving bell.
1535 - Guglielmo de Loreno developed what is considered to be a true diving bell.
1650 - Von Guericke developed the first effective air pump and used it to study the phenomenon of vacuum and the role of air in combustion and respiration.
1667 - Robert Boyle observed a gas bubble in the eye of viper that had been compressed and then decompressed. This was the first recorded observation of decompression sickness or "the bends."
1691 - Edmund Halley patented a diving bell which was connected by a pipe to weighted barrels of air that could be replenished from the surface.