The elite of commercial diving: living under pressure to work on the seabed for weeks.
Un saturation diver is a commercial diver who lives under pressure inside a hyperbaric chamber aboard a vessel, at the same pressure as the working depth, for days or weeks. They go down to work in a closed bell and return to the chamber without decompressing. They only decompress once, at the end of the whole campaign. It's the way to work at great depth continuously, and the best-paid tier of the trade.
When a diver goes down, their body absorbs inert gas (helium, nitrogen) due to the pressure. At shallow depth they can surface right away; at great depth, surfacing too fast would be fatal, so after each dive a very long decompression would be needed. Saturation diving solves this: instead of surfacing and descending every day, the diver stays under pressure. Their tissues become "saturated" with gas —they absorb all they can at that pressure— and from then on it doesn't matter whether 3 days or 3 weeks pass: the decompression required is the same. It's done only once, at the end.
The team lives in a saturation system: connected chambers where they eat, sleep and rest, always under pressure. To work, they enter the diving bell (bell), which seals, holds the pressure and descends to the bottom. There they exit through a hatch, with an umbilical supplying gas, hot water and communications, do their task —welding, cutting, inspection, assembly— and return to the bell. A team of Life Support Technicians control the atmosphere, temperature and timings from above.
Most commercial diving is "surface-supplied": the diver goes down from the vessel or quay with supply from above and comes back up the same day. Saturation is a world apart, for great depths and long jobs, and only a small portion of commercial divers reach it. Almost all start on surface-supplied work and some, with years of experience, make the jump.
A technique in which the diver lives under pressure in a chamber at the depth's pressure for days or weeks, and goes down to work in a closed bell. Because their tissues are already 'saturated' with inert gas, they only decompress once at the end of the whole campaign, not every day. This allows work at great depth continuously and safely.
Because after a certain time under pressure the tissues absorb all the inert gas they can at that depth: they are saturated. Adding more hours no longer increases the decompression needed, so it doesn't matter whether you stay 3 days or 3 weeks: you decompress only once.
The norm is 28 days under pressure, with an industry reference limit of 28 consecutive days of 'bell run' and several final days of decompression. Afterwards, an equivalent rest period on the surface.
It's one of the best-paid jobs precisely because of the risk and the demands. IMCA and regulator protocols have made it much safer, but it still requires strict medical fitness, specific training and absolute respect for procedures.
Educational guide · updated 6 August 2026