Diving at LNG terminals means inspecting and maintaining jetties, dolphins, fenders, water intakes and discharges, cathodic protection and pipework. What sets it apart isn't the diving technique, but the permit regime, the zone classification and the working windows between LNG carriers.
A liquefied natural gas terminal is, seen from land, a striking installation: cryogenic tanks, a flare, articulated loading arms and an LNG carrier berthed with its spherical or membrane-type hull. Seen from the water, though, it's quite a conventional marine structure. Piles, pile caps, fenders, dolphins, chains, pipework, water intakes. Nothing under the surface is exotic from a diving-technique point of view. What changes it completely, and what makes this work priced and organised differently, is the regime it's carried out under.
That's the distinction worth taking on board before considering going into this kind of contract. A diver can know perfectly well how to inspect a pile and still not be fit to work at an LNG terminal, because what the client is buying isn't the inspection: it's the certainty that the work is carried out without triggering an incident at an installation classified as critical.
What an LNG terminal looks like from the water
The usual layout is a jetty running out from the coast to sufficient depth, with a central platform holding the loading and unloading arms, flanked by berthing and mooring dolphins. The berthing ones carry the fenders that absorb the ship's energy as it comes alongside; the mooring ones take the lines and are usually fitted with quick-release hooks. The whole thing is linked by walkways and by a rack of cryogenic pipework running overhead.
Underwater, each of these elements has its submerged part: steel or concrete piles, sometimes jackets and encasements, pile caps, bracing, sacrificial anodes, chains and shackles on floating fenders where fitted, and scour protection at the seabed. The terminal also has water intakes and discharges, and pipework running from the installation out to sea or to other parts of the plant.
In some configurations there's a floating unit permanently moored, an FSRU, that regasifies on board. That adds elements of its own: the unit's mooring system, the interface between the unit and the jetty, and a very different discharge pattern, because regasification on board moves considerable flows and returns water to the sea noticeably colder than the intake water.
The typical jobs
Most of the workload is inspection. Visual and tactile inspection of piles along their full submerged length, looking for corrosion, loss of section, mechanical damage from contact, coating deterioration and weld condition. Ultrasonic thickness measurement at defined points, with the cleaning beforehand that requires. Reading cathodic protection potentials and checking the condition and consumption of the anodes, which at a berthing structure is one of the most useful indicators of how the whole thing is really ageing.
Next come the fenders and their fittings: tension and weight chains, shackles, eyebolts, anchor points. It's an element that works under fatigue every time a large vessel comes alongside, and its failure has direct consequences for operations, so it usually has its own inspection frequency.
The third block is water: intakes and discharge points. Cleaning screens and strainers, removing fouling and trapped material, inspecting the intake structures, checking there's no partial blockage cutting the flow. It's unglamorous, very recurring work.
The fourth is pipework. Inspecting the route, checking the coating, verifying burial and trench depth, detecting freespans — the free spans— and checking the condition of rock armour or concrete mattresses over the line. After a strong storm, this check stops being routine and becomes urgent, because a section left exposed or in freespan is a structural problem that doesn't fix itself.
And last, the unplanned work: searching for and recovering objects dropped in the water. A tool, a part, a piece of cargo securing gear. It seems minor, and it isn't: at an installation like this, an object not located on the seabed by the berth is an open item that can hold up operations until it's closed out.
Why the client is so demanding
This is where the real difference from an ordinary commercial port lies. An LNG terminal is a classified installation, subject to a major-accident-hazard control regime, with defined ATEX zones around the points where a flammable atmosphere could occur. That has very concrete consequences for the diving team.
The first is the permit to work. Nothing is done without a permit issued by the installation, with its associated risk assessment, its conditions and its time window. The permit isn't signed off by the diving supervisor: it's issued by the plant, and it can be withdrawn at any moment if process conditions change. A diver used to port works, where the site manager sets the pace, has to accept that here the pace is set by someone sitting in a control room looking at something else entirely.
The second is isolation and lockout. Any work on a water intake, a diffuser or a discharge requires the system to be isolated, locked out and tagged, with physical confirmation that the pump can't start while a diver is in the water. This is the point where serious accidents in industrial underwater work concentrate, and it's non-negotiable: without positive, verified and signed-off confirmation of isolation, nobody enters the water.
The third is zone classification. In ATEX areas, electrical and electronic equipment brought in is restricted. That affects cameras, lights, communication equipment, power tools, generators and the diving control panel itself, and it dictates where the surface equipment can be positioned. In practice this is usually solved by siting the spread outside the classified zone and working with longer hoses and umbilicals, which in turn has implications for the emergency plan and for the standby diver. It's worth understanding these restrictions properly before turning up with a commercial diving equipment list drawn up for conventional works.
The fourth is coordination. You need to talk to the plant control room, the port authority, the pilot if a manoeuvre is scheduled, and the ship if it's berthed. Communication can't be informal: a channel is set up, confirmed before entering the water, and kept open throughout the dive, with the option to pull the diver out immediately if the plant asks.
The working windows
The operational factor that defines this work more than any other is that the terminal exists to receive ships, and diving can't get in the way of that. When a carrier is berthed or manoeuvring to approach, the berth area is closed to diving. When the ship leaves, a window opens that can last hours or days depending on the arrivals schedule.
That produces a distinctive work pattern: long stretches of waiting and mobilisation with the equipment ready, followed by periods of intense execution where the whole planned scope has to be pushed through before the next ship arrives. Planning has to be much tighter than on a standard job: the scope is broken down into tasks that fit within the available window, with defined stopping points, so the work can be left in a safe state if the window shortens. An early-arrival notice for a ship can cancel an entire day's work.
Cold water, currents and visibility
There are two physical conditions specific to these installations worth anticipating. The first is the temperature of the discharge water. At a regasification terminal, the process draws heat out of the seawater, so the effluent returns to the sea colder than the ambient water. Near the discharge point there can be a noticeable temperature difference compared with the rest of the basin. For a diver, that means thermal protection estimated from the port's general water temperature can fall short, and the suit — and hot water, if used — needs to be planned around the specific work point, not the average.
The second is the currents generated by the pumps themselves. Near an active intake there's suction flow, and near a discharge there's a jet. Neither is a predictable tidal current: they appear and disappear according to the plant's operating regime, which the diver doesn't control. That's why checking pump status before every dive is part of the procedure, not a formality. On top of that, visibility in industrial basins tends to be poor and gets worse as soon as fouling starts being cleaned off a screen, which pushes the work towards touch and towards greater reliance on communication with the surface.
Documentation as the product
In this kind of contract, the deliverable isn't the repair: it's the report. The client needs a document it can feed into its asset-integrity system and present to an authority or an insurer. That means continuous video with a clear reference to the point inspected, photographs of defects with a visible scale, thickness measurement tables with the exact location of each point, cathodic potential readings referenced to the electrode used, and an explicit criterion for classifying findings.
The report also has to say what couldn't be inspected, and why. A diver who hands back a report claiming one hundred per cent scope coverage when the window was cut short is creating a bigger problem than the one they're solving. Honesty about actual coverage is, at critical installations, worth more than apparent thoroughness.
What profile is required and how you get in
The profile is a surface-supplied diver, with certification recognised by the client and current medical fitness, and with demonstrable experience inspecting port structures. Specific skills are usually added on top: ultrasonic thickness measurement, cathodic protection reading, visual inspection with sound judgement and report-writing ability. Many clients also ask for formal underwater inspector qualification, of the kind recognised internationally, because they need the report's sign-off to carry weight. The inspection certifications and qualifications branch carries more weight here than accumulated depth.
On top of all that, installation safety training is always required: site induction, explosive-atmosphere risk training, the permit system, and often survival and evacuation training if there's an offshore or floating-unit component. This training isn't transferable: every terminal runs its own, and it has to be repeated.
As for how you get in, the mechanism is indirect. No terminal hires divers directly. It contracts a subsea services provider through a framework inspection and maintenance contract, usually multi-year, and it's that provider who mobilises the team. So the route in is joining that provider's workforce or pool, which means identifying which contractors have an industrial portfolio and not just marine civil works. It's a market built on ongoing relationships more than on campaigns, and that shapes the kind of vacancy that appears: roles like this are often filled through internal movement or recommendation before ever reaching open job-search.
channels. It's worth noting, to finish, that this is surface-supplied diving from start to finish. Berth depths are moderate and the submerged infrastructure is within easy reach. It's not a route to the bell, and the path that leads to saturation work is a different one. What it does offer is continuity, a client who pays for work done and properly documented, and a kind of operational discipline that's valued afterwards at any industrial installation.
Frequently asked questions
What diving jobs are done at an LNG terminal?
Mainly inspecting piles and berthing structures, checking fenders and their chains and fittings, cleaning screens and strainers at water intakes, inspecting discharge points, reading cathodic protection and anode condition, and checking subsea pipework and its burial. On top of that there's searching for and recovering objects dropped in the water, which tends to be unplanned, urgent work.
Why is it more demanding than working at an ordinary port?
Because it's a classified installation with ATEX zones and a major-accident-hazard control regime. Nothing is carried out without a permit to work issued by the plant, any work on intakes or discharges requires verified isolation and lockout, electrical equipment is restricted in the classified zone, and coordination with the control room and the port authority runs continuously throughout the dive.
Do you need saturation diving to work at LNG terminals?
No. All the work is carried out with surface-supplied diving at moderate depths, the kind found at any port berth. The difficulty isn't in the depth but in the permit regime, the working windows between ships, and the standard of documentation required. Anyone looking to rack up bell days should look towards a completely different kind of contract.
How do the working windows between ships affect the job?
With a carrier berthed or manoeuvring, the berth area is closed to diving. Work is squeezed into the gaps between port calls, which produces a lot of waiting time with the equipment mobilised and periods of very intense execution. The scope is broken down into tasks that fit the available window, with defined stopping points so everything can be left in a safe state if the window is cut short.
What effect does the discharge water have on the diver?
At a regasification terminal the process draws heat out of the seawater and returns a colder effluent to the sea, so there can be a noticeable temperature difference near the discharge point. Thermal protection needs to be sized for the specific work point, not the port's average temperature. The pumps also generate unpredictable suction and jet currents.
What's required to get into this kind of contract?
Surface-supplied diving certification recognised by the client, current medical fitness, experience inspecting port structures, and specific skills such as thickness measurement, cathodic protection reading and report-writing. Formal underwater inspector qualification is usually required, along with installation-specific training every time, which doesn't carry over between terminals.
Published 10 September 2026 · By Arthur More, professional saturation diver
Photo: L.C.Nøttaasen · CC BY via Openverse