How long does a saturation diving campaign last, and what are the limits

The 28-day standard under pressure

In saturation diving the diver lives pressurised inside a system for the whole campaign, without returning to the surface until the end. That continuous stay can't be extended indefinitely: the human body has limits, and the industry works with well-established caps. The best known is roughly 28 días in saturation, a figure that has become the usual reference for planning campaigns.

That period isn't arbitrary. It reflects the need to balance the productivity of the operation with the diver's health and safety. Keeping a person under pressure for weeks demands very strict medical and environmental control, and extending that time would increase the physical and psychological toll. That's why, although the exact duration varies by project, the four-week range has become established as the reference pattern.

It's worth distinguishing between the duration of the campaign and that of a dive. In saturation diving it isn't a matter of going down and coming up each day, but of living pressurised for the whole block and going out to the seabed in shifts through a bell. If this way of working is new to you, what a saturation diver is we explain how the system works and why it's done this way.

The limits set by IMCA

The industry's main technical reference is IMCA, the international marine contractors association, which publishes codes of practice for offshore diving. Its documents guide aspects such as the duration of saturation, the diver's exposure, decompression rates and living conditions inside the system. Many companies adopt these guidelines as the basis for their procedures, alongside the applicable national regulations.

Maximum time in saturation

Industry guidelines set limits on the total time a diver can stay pressurised in a single campaign, and the reference figure usually used is around 28 days. The idea is to avoid excessively long exposures and to ensure that, after each campaign, the body has enough time to recover. The exact details depend on the current version of each guideline and on the regulations of the country where the operation takes place.

The final decompression

When the work finishes, the diver can't go straight back to atmospheric pressure. The body has been saturated with inert gas for weeks and needs to release it very slowly and in a controlled way to avoid decompression sickness. This final decompression takes place inside the system itself, reducing the pressure gradually, and can take several days depending on the storage depth. The deeper the saturation has been, the longer the ascent.

During these days the diver keeps living inside the system, no longer going down to the seabed, while the pressure drops gradually. It's a critical phase from a safety standpoint, continuously supervised by the surface team and medical staff.

The equivalent rest after the campaign

Leaving the system doesn't mean going straight into another saturation. After a campaign, the diver needs a recovery period before being able to pressurise again. Good industry practice includes an equivalent rest, that is, a surface interval proportional to the time spent in saturation, so the body can fully recover.

This rest isn't just a wellbeing recommendation: it's part of safety management. Stringing campaigns together without sufficient recovery would increase the physiological risk. That's why a saturation diver's life alternates intense blocks of pressurised work with long periods ashore. That pattern also shapes how pay works, something we cover in how much a diver earns.

What daily life inside the system is like

Living pressurised for weeks is a very particular experience. The diver and their teammates share a small space inside the saturation system, with pressurised living chambers where they eat, sleep and rest, and from which they access the bell to go out to the seabed. Everything is designed to keep environmental conditions controlled and safety constant.

The shift work cycle

Work is organised in shifts. While one team of divers goes out to the seabed through the bell, others rest or get ready inside the system. This rhythm makes it possible to use the operating window around the clock and spreads the workload across the team. Coordination with the surface crew is constant, since every excursion to the seabed has to be supervised from start to finish.

Food, sleep and hygiene under pressure

Daily life inside the system is shaped by the pressure and by the special atmosphere being breathed. Food is passed in through locks, sleep is organised around the shifts, and hygiene adapts to the confined environment. Voices sound different because of the breathing mixture, and controlling temperature and humidity is essential for comfort and safety. It's a demanding way of life that requires a level head, discipline and getting on well with the team.

All of this routine depends on highly specialised equipment, from the living chambers to the bell and the life-support systems. In equipment we go through the technical elements that make saturation possible, and in dive support vessels you can see the kind of platforms that house these systems.

What can shorten or lengthen a campaign

Although the reference pattern is around four weeks, the actual duration of each campaign depends on several factors:

• The scope of the project: a long subsea construction job may need the maximum number of days available, while a one-off inspection is resolved sooner.
• Sea conditions: weather can halt operations without taking the diver out of the system, lengthening the campaign without adding effective work.
• Storage depth: directly affects the length of the final decompression.
• Applicable regulations and guidelines: set the caps that can't be exceeded and the mandatory rest periods.
• The company's planning: each operator organises its campaigns according to its procedures and its fleet.

In practice, this means two divers can experience campaigns of different lengths even while working in the same sector. What stays constant is the framework: a reference limit of around 28 days, a slow decompression and a proportional rest period afterwards.

For anyone considering going into this speciality, understanding the duration and limits of a campaign is as important as knowing the training required. If you want to know how you get to work in saturation, how to become a commercial diver we go through the path from commercial diving to saturation.