Combat divers, expertly trained and resilient, rely on a wide range of kit, tough enough to support the execution of typically arduous, covert ops. From rebreathers to compressed gas systems, tactical dive submersibles and more, the gear used by the combat diver enables extreme missions to be undertaken, while ensuring that optimum life support and safety are maintained for the dive teams involved.
This article examines combat diving through expert eyes, touching on overall operational and equipment demands, some of the gear used, and by whom.
Qualified at depth and opening the conversation
Working in one of the harshest environments on Earth, military divers must be highly trained individuals at the peak of human physical and mental abilities, though also relying on critical equipment to support them. With its military diving expertise, subsea specialist company, JFD, announced in May 2024, that former senior Royal Navy (RN) officer, Peter Laughton MBE, had joined the company as its new Head of Military Diving. Laughton was formerly Royal Navy (RN) Commodore in the Middle East, commanding the International Maritime Security Construct and Coalition Task Force Sentinel. After 32 years of RN experience, including many years as a specialist mine clearance diving officer, Laughton will now oversee the ongoing development of JFD’s military diving systems, including for Special Operations Forces (SOF) divers, mine clearance operations, and a wide range of other missions. At the time of joining the company, he said, that having relied on JFD life support systems (LSS) throughout his naval career, he was looking forward to transferring that operational understanding to his work at the company.
ESD took the opportunity to ask Peter Laughton for his qualified insights on all things combat diving and began by touching briefly on how equipment has evolved and latest technologies and innovations have enhanced safety and reliability. According to Laughton, “Combat diving equipment has evolved considerably, and while the fundamentals of a diving rebreather have not really changed, i.e., a counterlung, gas supply, regulator and CO2 scrubber, what has changed immeasurably are advances in equipment monitoring, both remote and personal, making military diving much safer. Electronics, for example, are now used to strictly control, monitor and alert the diver to changes in the partial pressure of O2 in the diving loop, as well as manage decompression.”
On a fairly typical combat diving kit list, essential gear will include a military diving rebreather, as Laughton alluded, to sustain life underwater; an exposure suit of some sort – wet or dry suit – to protect divers from the elements; a face mask and fins; and, in some cases, a diver-propulsion device to allow swimming over greater distances. “There are a range of short- and medium-distance diver-propulsion devices on the market designed to allow divers achieve greater range and operational effect.” In addition, and depending on the mission, divers will also carry other ancillary equipment, such as personal weapons, fighting equipment, radios, compasses, and watches. Compressed gas cylinders might also be used instead of a rebreather dependent on the mission.
Preparing for a dive – deep and shallow
Laughton stressed that any form of civilian or military diving is inherently hazardous and, therefore, requires a systematic approach when preparing for a dive or combat mission. Whether scuba, or combat diving, equipment set-up and preparation is fundamental to the safe execution of the mission. No matter the equipment, new or old, safety relies on everything a diver needs for a particular mission being checked and re-checked before deploying. If a diver’s equipment malfunctions through incorrect set-up, or general failure of any of the parts, then the mission is potentially compromised. Before every dive, combat divers will check their personal equipment and then conduct a series of other pre-dive checks to ensure the equipment is functioning correctly. This stage includes several in-water checks, such as testing for gas leaks, and then ensuring that all parts of the equipment are functioning as expected. Laughton notes that, “As with any highly technical equipment, which is routinely operated in arguably the harshest environment on the planet, the need for routine and planned maintenance and servicing is essential for both diver safety and mission accomplishment.”
On the subject of deep versus shallow dive operations, Laughton emphasised clear distinctions. For example, training – JFD has its own range of ex-military-instructor-led military diver training courses – varies considerably, because the requirement to go deep can introduce much greater risk, as well as the need for decompression, procedures and equipment. Here, the quality of training is critical, especially when operating in such an unforgiving operational environment where mission success can be fundamental to national security. “Going deeper is usually for shorter periods to effect a mission on the seabed, such as mine clearance operations, although this might also be conducted, and necessary, in shallow waters,” Laughton said. He added that combat swimmers tend to spend most of their time at a shallow depth, but much depends on the mission and they must be prepared to go deeper, if required, for a variety of operational reasons, e.g., when exiting a submarine. The dive equipment for shallow and deep diving can also vary considerably; on deeper dives, for example, gas is used up more quickly, making sufficient back-up gas needed if a diver is to safely reach the surface in the event of an emergency equipment failure of their primary system.
Catching a lift
When it comes to submersibles for combat divers, the discussion moved to Tactical Diving Vehicles (TDVs), which, Laughton said, act as force multipliers for maritime SOF, greatly enhancing operational capabilities. With a re-focus on maritime operations amongst NATO and its allies, as the littoral operational battlespace evolves to meet an increasing range of threats, JFD’s new head of military diving stressed that the relevance of TDVs has never been more apparent. These craft are increasingly seen as a vital component of current and future SOF littoral and underwater manoeuvre operations; they bridge critical capability gaps, enhance operational capability, whilst also increasing mission success probability when operating in complex, high-threat littoral environments. TDVs emerge as a viable solution for both discreet and covert littoral operations, and for specialist amphibious reconnaissance and raiding forces that do not have a tactical diving capability, the ability of TDVs to operate in a semi-submerged mode significantly reduces the vehicle’s signature, which provides a means of discreet infiltration and exfiltration not offered by conventional surface raiding craft when operating in high-threat areas, thereby reducing the probability of mission compromise. Laughton also said that besides their operability with larger insertion / extraction-support platforms, the long-range capability of TDVs, such as JFD’s own Carrier Seal vessel, offer SOF units what he called “an independent, organic, over-the-horizon capability”. This not only increases operational flexibility at a unit level, but also enables the employment of multi-mode TDVs without exposing high-value assets, such as submarines and surface ships, to unnecessary risk. He added that for navies that lack submarines capable of supporting TDV operations, these vehicles are a cost-effective alternative, enabling maritime SOF the ability to cross an expanding ‘water gap’ and conduct operations that would otherwise be beyond their reach. Laughton added that, “The versatility and relatively low cost of TDVs, compared to larger platforms, make them an attractive option for maritime security providing rapid response, coastal defence, and critical national infrastructure protection.”
As for the specialist training required for a combat diver to operate such submersibles, Laughton referenced the company’s products, saying that training really depends on the size of the TDV, depth requirements, mission complexity, approach and the mission itself. “Our smaller TDVs employ a ‘Gameboy controller’ approach, for the very purposes of rapid training and ease of use; our larger variants are slightly more complex. However, basic craft handling, which includes diving, surfacing, trim and buoyancy procedures, is very easy.” Conversely, he said that extended underwater diving in GPS-denied conditions, and at depth, are another matter and where the core of diver/TDV training would ordinarily focus to ensure that both pilot and co-pilot of a two-man vessel would ordinarily be capable of “flying, or commanding, the craft”, by themselves, if required.
The company’s own systems, which operate with several unnamed navies, globally, include the Carrier Seal Laughton mentioned; this is an eight-man craft designed at the company’s facility in Sweden. Powered by a diesel engine, the 10.45-metre-long, 4,000 kg TDV has a beam of 2.23 m and can carry a payload, including its commander/pilot, driver/co-pilot, crew of six SOF divers, and mission-related equipment, totalling 1,000 kg. The crew sit at the forward controls, passengers sit behind them protected within the hull, but with overhead access panels. For navigation, the TDV’s steering information navigation and control system combines data from GPS, gyro compass, depth sounder, obstacle avoidance sonar and doppler velocity log sources to ensure safe passage, and its optronic sensor suite, installed on top of its height-adjustable tactical mast, comprises thermal imaging, colour TV camera, GPS and navigation lights. The TDV can reach surface speeds of 30 kn and achieve a range of 150 NM traveling on the surface, with submerged speeds up to 5 kn and a 15 NM range if submerged; lengthy submerged ops typically require additional batteries. The vessel can also operate semi-submerged, displaying minimum surface signature if the tactical situation requires it, as Laughton alluded. A spare fuel bag and more batteries can also give the Carrier Seal an additional 75 NM range. Typically, after a surface approach to an objective, the final stage of a covert operation would be sub-surface, travelling at 4 kn; as far as the maximum depth the TDV can undertake, this is largely dependent on the LSS worn by the divers onboard.
Of any new tactical submersibles in the JFD pipeline to add to its current range along with the likes of its Carrier, Shadow, Dry Sub/Wet Sub Seal TDVs, Laughton said that, “JFD is exploring future platform enhancements, such as hybrid craft opportunities, enabling manned and unmanned interoperability to enhance versatility for modern day operations.” He said that by integrating diver monitoring technologies and advanced LSS, as well as integrating onboard data systems to provide a unified communication and information platform for divers, this would enhance both mission planning, real-time operational effectiveness, and safety.
Rebreather basics and comparisons
As Laughton highlighted above, the rebreather is probably the key piece of combat diving equipment for SOF covert ops. In recreational or military scuba diving, a more widely used and recognised self-contained, aluminium-cylinder-based, compressed-air, open-circuit, underwater breathing system is used, which, when the diver exhales underwater, releases that exhaled air as bubbles to the surface, which are visible to the naked eye and infra-red, so easily detected by an enemy during a military operation. This is where the compact and relatively lightweight rebreather comes to the fore, as a closed-circuit diving system; as the diver breathes, it scrubs/filters their exhaled breath, removing carbon dioxide (CO2) and recycling any unused oxygen, though with pure oxygen added as required, back to the diver. No bubbles are released from a rebreather and operatives remain undetected at the surface. Its efficiency in recycling and controlling the use of oxygen offers the added advantage of long-duration dives, potentially up to some four hours at a time, which opens up several operational possibilities, including being able to approach key onshore locations from disembarkation points far out to sea, possibly from a submarine, or other tactical insertion vessel.
Buoyancy is another key issue advantaged through the use of a rebreather, unlike in a typical open-circuit, scuba system; in the open-circuit system, the compressed gas pressure is reduced so it fits into the diving cylinder and the diver breathes that air in at a higher volume than it was in the tank. With each inhalation the diver becomes slightly more buoyant, as a result, but with each exhalation he will descend very slightly. Using a rebreather with its closed-circuit system, however, such buoyancy issues do not arise, because between the breathing apparatus and the diver’s lungs, gases simply recirculate at a constant volume.
Now let’s look at one specific combat diving user group – the US Navy SEALs.
SEAL deal
In the world of combat diving, US Navy (USN) SEALs are often cited, so it’s well worth a look to see what categories of open-circuit and closed-circuit diving gear these proficient combat divers – as well as other US SOF diving units – use to conduct their operations.
Under these two closed and open categories fall three kinds of underwater breathing gear used by SEALs. The first is open-circuit scuba equipment, which typically comprises two aluminium compressed air cylinders, known as Twin 80s, because they each hold 80 cubic feet of oxygen. These can be used in various underwater operations including by divers and crew aboard TDVs. Cylinder size and weight, together with the release of bubbles, as mentioned above, are drawbacks using this system.
The second system is one of two closed-circuit systems used by SEALs and various SOF – the Dräger LAR V rebreather. Suited to shallow-water operations, the relatively small, front-worn LAR V is a closed-circuit scuba equipment, designated the MK 25 by the USN; it uses 100% pure oxygen, recycling expelled breath, filtering CO2 and adding the pure oxygen to supplement the increasingly, oxygen-depleted, recycled breath, as previously outlined, and eliminating all bubbles to the surface. As a result, this rebreather is suited to covert ops, and can operate down to approximately 20 m; this, however, is less than achievable depths using open-circuit scuba equipment using Twin 80s; dive duration is also affected by depth, water temperature and oxygen consumption rate.
The third type of gear used by SEALs, of which two systems – the MK 15 and MK 16 – are in use, is also a closed-circuit rebreather, although this time they operate using mixed gas instead of pure oxygen. They follow the same CO2 filtering process as the LAR V, but instead of using pure oxygen to supplement the recycled breath, both these rebreathers dilute the oxygen with another gas – air, Timux, or Heliox – creating a mixture, which maintains a partial pressure of oxygen level, thereby enabling much deeper dives to be achieved, (around 600 msw), than with the Dräger system.
It is worth noting that Dräger now markets the Dräger 8000 rebreather as its most advanced all-purpose solution, which, unlike the LAR V, can be worn on either the front or the back of the diver. The latest system offers typical closed-circuit functionality, or semi-closed-circuit operating that can enable greater depths to be achieved using nitrox. Its design is said to produce very low breathing resistance for the diver, thereby improving their overall breathing performance underwater, all adding to operational effectiveness and safety in the underwater environment where the ability to breathe is a constant challenge. The system has an adjustable lung demand valve, which allows the diver to switch between easy, medium comfort, and harder breathing settings, the latter typically selected when ascending tactically. All components of the LAR 8000 have been designed and tested in accordance with STANAG 2897 Class A, meaning the equipment is a completely non-magnetic diving device.
The company’s Panorama Nova Dive full-face mask is recommended for use with the Dräger 8000; the basic mask has a five-point harness to ensure an optimum seal is achieved around the diver’s head, with three ports in the mask offering different set-up configurations depending on the rebreather or compressed-air systems to be used, as well as different underwater communication systems that might be employed during a mission. An exhalation valve at the bottom of the mask enables the diver to expel any water that might enter during extreme arduous situations, though under normal operating conditions, the company says water ingress is unlikely. A modified version of the mask can be fitted with a mechanical, low-pressure alarm to warn a diver of low air supply, particularly useful in low visibility when it acts as a precaution against human error.
The company says that its Panorama Nova Dive R mask has been tested the US Navy Experimental Diving Unit (NEDU) and approved by them for use with the Dräger LAR V MK 25 Mod2 rebreather. The approved version has an adjustable, two-position mouthpiece and oral-nasal configuration to reduce the build-up of CO2.
Best combat diver footnote
Having only recently taken place, in June 2024, mention of the US Army’s ‘Special Operations Command Best Combat Diver Competition’, (USASOC), at US Special Forces Underwater Operations school at Fleming Key, at Key West’s northern point in Florida, makes a worthy footnote. Underpinning the reliance and care combat divers must have for one another, the competition, according to a statement, is designed to build camaraderie and trust between divers, as well as put an operative’s full range of necessary skills – academic, physical, mental, adaptability – to the test, including equipment validations of a wide range of kit, such as rebreathers and gas tanks and all LSS-related gear and peripherals typically used to support extreme, tactical, underwater combat-diving scenarios; operations involving such procedures as airborne insertion and submarine work were also tested. Teams competing were from US Army Special Forces, US Marine Special Operations, and US Air Force Special Operations, with this year’s winner the combat diver team from the 10th Special Forces Group of the US Army’s Special Forces.
The final point here is about the diver, for no matter the combat diving kit and systems being used, from rebreathers to compressed gas cylinders, tactical diving vehicles, to deployment and insertion by submarine, it is down to the calibre, training, resilience and prowess of the individuals who make up the global SOF combat diver community, that will ensure best use is made of the equipment involved, new or old, and for any mission to be a success.
Tim Guest
Author: Tim Guest is a freelance journalist, UK Correspondent for ESD, and a former officer in the British Forces.