First escape from a submarine

The early history of submarine development is littered with tragedies as it was impossible for the crew of a sunken submarine to be rescued, until the invention of the submarine rescue chamber, first used in 1939.

Prior to that, the only hope submariners had was saving themselves. The first time this happened was on 9 June 1931 when the British submarine HMS Poseidon, then operating in China, was accidentally rammed by the cargo ship Yula and sank near the British naval base at Weihai, Shandong.

Just over half of the crew members managed to scramble off Poseidon before it sank, but 26 got trapped on board. Fortunately for those stuck on the boat, Poseidon was equipped with innovative underwater breathing gear known as the "Davis Underwater Escape Device" or "Davis Submerged Escape Apparatus" – a prototype of what would later become scuba equipment.

Eight men attempted to reach the surface using this equipment, but only five of them survived.

Although they survived the wreck, the five that successfully used the oxygen rebreathers suffered life-long medical problems, caused by decompression sickness.

The "Davis Underwater Escape Device" (aka Davis Submerged Escape Apparatus, or DSEA) was invented by Sir Robert Davis (director of diving equipment maker Siebe Gorman) in 1910.

In the 2010s, news emerged that the Chinese Navy secretly salvaged Poseidon in 1972.

The first successful submarine rescue using a rescue chamber was of the USS Squalus (SS-192) crew on 23 May 1939. The diesel-electric submarine sunk after a valve failure during a test dive off the Isle of Shoals, near the coast of New Hampshire, USA. The following day, a McCann rescue chamber (inspired by Vice Admiral Charles B. Momsen’s diving bell) was lowered from the USS Falcon (ASR-2) and all 33 people on board the Squalus were saved.