Timeline of underwater technology:

- Several centuries BC: Relief carvings made at this time show (An ancient kingdom in northern Mesopotamia which is in present-day Iraq) Assyrian soldiers crossing rivers using inflated goatskin floats. Several modern authors have wrongly said that the floats were crude breathing sets and that they show (Click link for more info and facts about frogmen) frogmen in action.)

- 1300 or earlier: Persian divers using diving goggles with windows made of the polished outer layer of tortoiseshell.

- 15th century: Leonardo da Vinci made the first known mention of air tanks, in his Atlantic Codex, that systems were used at that time to artificially breathe under water, but he did not explain them in detail due to what he described as "bad human nature", that would have taken advantage of this technique to sink ships and even commit murders. Some drawings, however, showed different kinds of snorkels and an air tank (to be carried on the breast) that presumably should have no external connections. Other drawings showed a complete immersion kit, with a plunger suit which included a sort of mask with a box for air. The project was so detailed that it included a urine collector, too.

- 1531: G Roman Emperor uglielmo dives on two of Caligula's sunken galleys using a diving bell from a design by Leonardo da Vinci.

- Around 1620: Cornelius Drebbel may have made a crude rebreather.

- 1772: Sieur Freminet tried to build a SCUBA device out of a barrel, but died from lack of oxygen after 20 minutes, as he merely recycled the exhaled air untreated.

- 1776: David Brushnell invents the first submarine to attack another ship, the Turtle. It was used in the American Revolution.

- 1800: Robert Fulton builds the first practical submarine, the Nautilus

- 1825: William H. James designs a self contained diving suit that had compressed air in a iron container worn around the waist.

- 1829: Charles and John Deane, of Whitstable in Kent in England, designed the first air-pumped diving helmet. It is said that the idea started from a crude emergency rig-up of a fireman's water-pump (used as an air pump) and a knight-in-armour helmet used to try to rescue horses from a burning stable.

- 1837: Following up Leonardo's studies, and those of Halley the astronomer, Augustus Siebe developed standard diving dress, a sort of surface supplied diving apparatus.

- Around 1842: The Frenchman Joseph Cabirol started making standard diving dress.

- 1856: Wilhelm Bauer starts the first of 133 successful dives with his second submarine Seeteufel. The crew of 12 is trained to leave the submerged ship through a diving chamber.

- 1860: Ivan Lupis-Vukic, a retired engineer of the Austro-Hungarian navy, demonstrates a design for a self-propelled torpedo to emperor Franz Joseph.

- 1863: CSS Hunley is the first submarine to sink a ship Confederate States Navy during the Civil War.

- 1865: Benoit Rouquayrol and Auguste Denayrouze designed a diving set with a backpack spherical air tank that supplied air through the first known demand regulator. The diver still walked on the seabed and did not swim. This set was called an aérophore. But pressure cylinders made with the technology of the time could only hold 30 atmospheres, and the diver had to be surface supplied; the tank was for bailout. The durations of 6 to 8 hours on a tankful without external supply recorded for the Rouquayrol set in the book "Twenty Thousand Leagues under the Seas" by Jules Verne, are wildly exaggerated fiction. Judging by Jules Verne's inaccurate attempts in the book at describing how the Rouquayrol set worked, how the demand regulator works was not generally known or had already been forgotten when he wrote the book, which was published in 1870. But Jules Verne knew about the tendency of some divers surfacing into rain to want to stay underwater to keep out of the rain.

- 1866: Minenschiff, the first self-propelling torpedo, developed by Robert Whitehead, demonstrated for the imperial naval commission on 21 December.
In the late 19th century and after, industry could make high-pressure air and gas cylinders. That prompted a few inventors down the years to design open-circuit compressed air breathing sets, but they were all constant-flow, and the demand regulator did not come back until 1939.

- 1879: Henry Fluess invented the first closed circuit breathing device using stored oxygen and adsorption of carbon dioxide by a caustic soda or rebreather for the rescue of mineworkers who were trapped by water.

- 1893: Louis Boutan invented the first underwater camera.

- 1908: John Haldane, Arthur Boycott, and Guybon Damant published "The Prevention of Compressed-Air Illness", detailed studies on the cause and symptoms of decompression sickness.

- 1912: Haldane, Boycott and Damant published the U.S. Navy tested tables.
1915: Sir Robert Davis invented an oxygen rebreather called the "Submarine Escape Apparatus" to escape from sunken submarines. It was the first rebreather to be made in quantity. After that, various sorts of industrial oxygen rebreathers were made down the years for use in unbreathable atmospheres on land.

- 1916: Release of the first filming of Twenty Thousand Leagues Under the Sea. In filming the diving scenes, the actors used Oxylite rebreathers, likeliest connected to heavy helmet-type bottom-walking diving gear. In the 1930s sport spearfishing became common in the Mediterranean, and spearfishers gradually developed the common sport diving mask and fins and snorkel, and Italian sport spearfishers started using oxygen rebreathers.

- 1918: Ohgushi patented "Ohgushi's Peerless respirator". It was a constant-flow diving and industrial open-circuit breathing set. The user breathed through his nose and switched the air on and off with his teeth.

- Early 1930s: In France, Guy Gilpatrick invented waterproof diving goggles.

- 1933: Yves Le Prieur invented a constant-flow open-circuit breathing set. It could allow a 20 minute stay at 7 meters and 15 minutes at 15 meters.

- 1933: In France, Louis de Corlieu patents the first swimming fins.

- 1933: In San Diego (USA) the first sport diving club started, called the Bottom Scratchers: it did not use breathing sets or fins as far as is known.
- 1934: Charles Beebe dives to 3028 feet using a bathysphere.

- 1935: On the French Riviera the first known sport diving club started. It used Le Prieur's breathing sets. Its air cylinder was often worn at an angle to get its on/off valve in reach of the diver's hand; this would have caused an awkward skew drag in swimming.

-1939: the Frenchman Georges Commeinhes developed a two-cylinder open-circuit apparatus with demand regulator. The regulator was a big rectangular box between the cylinders. He offered this set to the French Navy, which could not continue developing uses for it because of WWII. In July 1943 he reached 53 meters (about 174 feet) using it off the coast of Marseille, But he died in 1944 in the liberation of Strasbourg in Alsace.

- 1939: Dr. Christian Lambertsen in the USA designed a 'Self-Contained Underwater Oxygen Breathing Apparatus' for the U.S. military. It was a rebreather. It was the first device to be called SCUBA.

- 1941: During WWII, Italy used rebreathers were used for one of the best known and most spectacular war actions: see Human torpedo.

- 1943: Jacques Cousteau and Emile Gagnan invented an open-circuit diving breathing set, using a demand regulator which Gagnan modified from a demand regulator used to let a petrol-driven car run on a big bag of coal-gas carried on its roof during wartime shortages of petrol. Cousteau has his first dives with it. This set was later named the Aqua-Lung. This word is correctly a trade name that goes with the Cousteau-Gagnan patent, but in Britain it has been commonly used as a generic and spelt "aqualung" since at least the 1950's, including in the BSAC's publications and training manuals, and describing scuba diving as "aqualunging". In October 1944 Frédéric Dumas reached 62 meters (about 200 feet) with this set.

- 1948: Auguste Piccard sends the first bathyscaphe, FNRS-2, on unmanned dives.

- 1950: Cousteau's Aqua-Lung became available (but very expensive) to industry and civilians in Britain. Siebe Gorman made it at Chessington.

- 1953: The National Geographical Society Magazine published an article about Cousteau's underwater archaeology at Grand Congloué island near Marseilles, and in French-speaking countries a diving film called Épaves (= Shipwrecks) came out. That started a massive public demand for aqualungs and diving gear, and in France and America the diving gear makers started making them as fast as they could. But in Britain Siebe Gorman kept aqualungs expensive, and many British sport divers had to use home-made breathing sets and ex-armed forces or ex-industry rebreathers, and some became expert at home-making diving demand regulators from industrial parts such as Calor gas regulators. Finally Submarine Products Ltd, in Hexham in Northumberland in England, designed round the Cousteau-Gagnan patent and made sport diving breathing sets accessibly cheap. In those times, free-swimming diving suits were not readily available to the general public, after the first rush of war-surplus frogman's drysuits ran out, and as a result many scuba divers dived in merely swimming trunks. That is why scuba diving used often to be called "skindiving".

1953: Captain Trevor Hampton founded the British Underwater Centre at Dartmouth in Devon, England.

- 1953 October 15: The BSAC was founded.

- 1954: USS Nautilus, the first nuclear-powered submarine, is launched.

- 1954: The first manned dives in the bathyscaphe FNRS-2.

- 1956: The first wetsuit was introduced.

- 1957 to 1961: The television series Sea Hunt introduced SCUBA diving to the television audience.

- 1958: USS Nautilus completes the first ever voyage under the polar ice to the North Pole and back.

- 1960: Jacques Piccard and Lieutenant Don Walsh, USN, descend to Challenger Deep, the deepest known point in the ocean (about 10900m or 35802 feet) in the bathyscaphe Trieste.

- 1960: USS Triton completes the first ever underwater circumnavigation.

- 1965: The film version of James Bond in Thunderball came out and helped to make scuba diving popular.

- 1971: Scubapro introduces the Stabilization Jacket, or Buoyancy Compensator, in England commonly called stab jacket.

- 1983: The Orca Edge dive computer was introduced.

- 1985: The wreck of RMS Titanic was found.

- 1989: The film The Abyss helped to make scuba diving popular.