Marine aquaculture employs divers to inspect and repair nets, check moorings, remove dead fish and change netting. It's shallow, repetitive work that's more accessible than offshore, with its own risks — net entanglement and highly repetitive dive profiles — that have driven specific regulation in the countries with the most production.
When people talk about commercial diving, the image that comes to mind is oil: platforms, bells, the North Sea. But there's a sector that employs divers every day of the year, that grows with global demand for protein, and that barely features in the coverage: marine aquaculture.
What a diver does at a fish farm
An open-sea grow-out site is a set of floating cages with nets hanging below the surface, held by a mooring system of anchors, chains and buoys. All of that is submerged, exposed to current and to biofouling, and needs constant checking. The typical tasks are:
- Net inspection: looking for tears, wear and weakened seams. A hole means fish escaping, a direct financial loss, and an environmental problem from farmed species getting out.
- On-site repair, stitching the netting underwater when the damage allows it.
- Net changes, a heavy operation carried out in campaigns that requires coordination with a crane and a vessel.
- Removing dead fish: collecting the dead fish that build up on the bottom of the cage, both for health reasons and because they attract predators.
- Mooring inspection: anchors, chains, shackles and lines, checking for wear and burial.
- Cleaning and biofouling control, though this is increasingly done with robotic washing equipment.
- Recovering dropped items and supporting surface maintenance operations.
The risks specific to this work
Depth is modest — rarely more than thirty metres — and that creates a false sense that it's easy diving. Documented accidents in the sector say otherwise, and their causes are fairly specific:
- Entanglement in the net. It's the characteristic hazard. Flexible netting, current, reduced visibility and a diver whose gear can snag form a combination that has killed people. Working inside or near the net calls for an umbilical, constant communication and a buddy.
- Perfiles repetitivos. Many short, shallow dives a day, day after day, build up an accumulated inert gas load that standard tables don't always cover well. It's a recognised cause of decompression sickness in the sector.
- Current and sea state at exposed sites, which is where modern production tends to be moving.
- Cold water and long working days, with the thermal strain that brings.
- Vessel traffic and crane operations over the diver's vertical line.
- Substances used in health treatments for the fish, which require observing withdrawal periods and procedures before entering the water.
The professional response to all of this is the same as in any other branch: surface-supplied diving instead of self-contained equipment whenever possible, hard-wired comms, a qualified supervisor at the dive point, a standby diver, and a risk assessment that's genuine for each task. Where the sector has run into problems has been precisely where diving has been done under recreational or fishing-diving arrangements instead of professional ones.
Where the demand is
The work is concentrated where intensive sea-cage production is:
- Norway, the world's largest producer of Atlantic salmon, with a highly mechanised industry, demanding labour regulation, and mandatory professional certification for service diving.
- Scotland and Ireland, with salmon and a British regulatory framework.
- Islas Feroe, with production that's intense relative to its size.
- Chile, the world's second-largest producer of salmonids, with very high demand for divers and an accident history that has driven successive rounds of tighter regulation.
- Mediterranean: Greece, Türkiye, Spain and Italy, with sea bass, sea bream and tuna farming.
- Canada, Australia and New Zealand, with their own production and established regulatory frameworks.
In Spain, the work is associated with sea bass and sea bream farms in the Mediterranean and in the Canary Islands, and with tuna traps and tuna farms. The professional diving schools in the country train a good part of that workforce.
Seasonality and conditions
It's not a sector with offshore's rotation structure. Contracts with local service companies predominate, along with day-rate work and moving between sites in the same area. There are clear peaks: net changes and mooring work cluster around fair-weather windows and dates in the production cycle, while routine inspection is continuous.
On pay, it's worth being realistic: aquaculture pays well below saturation diving and, generally, below construction offshore. In exchange it offers something many people value more than it seems: sleeping at home. It's one of the differences covered in inland diving versus offshore, and the general pay figures for the trade are in how much a diver earns.
What training is required
The requirements depend on the country, but the pattern is common: you need a professional surface-supplied diving certification recognised by the relevant labour authority, a current medical fitness certificate, first aid and oxygen administration training, and in many cases specific maritime safety training. Norway and Chile apply their own regimes and don't always automatically recognise foreign qualifications, which is worth checking before moving.
As an entry point into the trade, aquaculture has a notable advantage: it builds up logged dives and real practical experience in a short time, which is exactly what someone who's just qualified is missing. Many professionals working offshore today started out stitching nets. If that's where you are, it's worth reading how to start with no experience, revisar the recognised certifications and checking the current listings in the jobs section.
What a typical day looks like
The day starts early at the jetty, with the service boat loaded with the compressor or the cylinder bank, the umbilical, the helmets, the tools and the net-mending kit. The run out to the site can be a few minutes or a good hour, depending on how exposed the location is.
Once there, the sequence is the usual one for professional diving: pre-dive briefing, task allocation, equipment check, isolating whatever needs isolating — boat propellers, automatic feeders, treatment systems — and the first diver going in with the second ready on deck. The dives are short and run back to back through the day, with the supervisor keeping track of each one's times and surface intervals.
What surprises people most coming from other kinds of diving is the physical load out of the water. Handling sodden nets, hauling up dead fish, moving ballast weights and working from a small boat in a swell tires you out as much as the dive itself, if not more.
The relationship with the producer
In aquaculture, the client isn't an energy company with a technical department: it's usually the site manager, someone who knows their cages inside out and needs quick, understandable answers. A diver who can explain what they saw, point it out on a site plan and suggest a repair priority is worth far more than one who just carries out tasks. In practice, that ability to communicate is what turns an aquaculture diver into the one who gets the call first.
What weighs most in choosing this path
It's worth deciding this with your eyes open. Aquaculture offers continuity, being close to home, and a fast learning curve in skills that go on to serve in any other branch: handling an umbilical, working in current, orientation in low visibility, and communications discipline. What it doesn't offer is offshore pay or an automatic path into saturation. Anyone using it as a stepping stone should plan from the start how they're going to build up the dives and the competencies the next employer will ask for, and keep an immaculate logbook from day one.
Frequently asked questions
What exactly does a diver do at a fish farm?
They inspect and repair the cage nets, take part in net changes, check the mooring system, remove dead fish from the bottom of the cage, control biofouling, and recover dropped items.
Is diving in aquaculture dangerous?
It has its own well-documented risks: net entanglement, highly repetitive dive profiles that favour decompression sickness, current, cold water, and surface operations over the diver's vertical line. The shallow depth doesn't make it easy diving.
How much does aquaculture pay compared with offshore?
Considerably less than saturation diving and, generally, less than construction offshore. In exchange, it lets you work close to home without long rotations away.
Which countries have the most demand for aquaculture divers?
Norway, Scotland, Ireland, the Faroe Islands, Chile, the Mediterranean countries producing sea bass, sea bream and tuna, and Canada, Australia and New Zealand.
Does it work as a first job for a newly qualified diver?
Yes, it's one of the more accessible ways in. It lets you build up logged dives and practical experience in a short time, which is exactly what the offshore market demands afterwards.
What qualification is needed?
A professional surface-supplied diving certification recognised by the country's labour authority, a current medical fitness certificate, and training in first aid and oxygen administration. Norway and Chile apply their own regimes that don't always recognise foreign qualifications.
Published 24 August 2026 · By Arthur More, professional saturation diver
Photo: Sam Beebe · CC BY via Openverse