The rebreather's long road
Rebreathers came before scuba. It took more than a century for them to become everyday kit for technical divers. A short history.
Read this first Information, not instruction. Nothing here replaces training with a qualified instructor.
It's easy to think of the rebreather as the newest thing in diving. In fact, working rebreathers existed decades before the Aqua-Lung. What took time was making them safe for anyone other than military specialists.
- 1878
Fleuss's oxygen rebreather
Henry Fleuss builds a working closed-circuit oxygen rebreather using a rope soaked in caustic potash to absorb carbon dioxide.
- 1880
The Severn Tunnel
Diver Alexander Lambert uses a Fleuss set to close a flooded door deep inside the Severn Tunnel works.
- 1940s
War and frogmen
Italian and British combat swimmers use oxygen rebreathers for covert attacks. In the US, Christian Lambertsen develops his own unit for military use.
- 1968
The Electrolung
One of the first electronically controlled mixed-gas rebreathers is sold to civilians. It's withdrawn after deaths and reliability problems.
- 1997
The Inspiration
The Inspiration electronic CCR goes on sale and brings closed-circuit diving to technical divers.
- 2005
Boesmansgat
Dave Shaw dies at around 270 m. The analysis of his dive shapes thinking about CO₂ retention and work of breathing.
Oxygen and its limits
The first rebreathers used pure oxygen. They were simple, silent and produced no bubbles, which made them ideal for military work. But oxygen becomes toxic at quite modest depths, so pure oxygen rebreathers were limited to shallow water, generally within the first several metres.
Christian Lambertsen, who developed rebreathers for the US military in the 1940s, is also credited with coining the word SCUBA: self-contained underwater breathing apparatus.
Mixed gas and electronics
To go deeper, a rebreather needs to add a diluent gas and hold the oxygen level at a safe setpoint. That requires sensing oxygen and controlling it. Military units developed in the 1960s and 70s, such as the US Navy's Mk 15 series, did this with oxygen sensors and electronics.
The Electrolung, released for civilians in 1968, tried to bring that technology to sport divers. It was ahead of its time and had problems with reliability and support. After deaths, it was withdrawn.
The technical diving era
In the 1990s, technical divers wanted what rebreathers offered: huge gas savings on expensive trimix, optimal mixes at every depth and warmer, moister gas. The Inspiration, launched in 1997, was the first electronic CCR widely sold to them. Manual CCRs, which rely on the diver to add oxygen, also developed a following in the same period.
Rebreathers opened up dives that would be impractical on open circuit. They also brought their own failure modes.
New ways to get hurt
On open circuit, if a diver breathes the wrong gas, they usually know which cylinder it came from. On a rebreather, the gas in the loop changes constantly. A failed sensor, an empty oxygen cylinder or an exhausted scrubber can produce hypoxia, hyperoxia or carbon dioxide build-up, often with no clear warning.
Accident reviews have repeatedly pointed to missed pre-dive checks, diving beyond training and poor bailout planning. Many divers now use written checklists before every dive, an idea borrowed from aviation.
Today
Rebreathers are now a normal part of technical diving, with European standards for design and testing, and a wide range of units. The debate has moved from whether rebreathers are safe to how best to use them: how much bailout to carry, how to manage scrubbers, and how to train for failures that can't be seen.