Singapore deploys new Combatant Craft Underwater to support Special Forces in stealth beach landings.

On June 10, 2025, the Singaporean Navy introduced its Combatant Craft Underwater (CCU), which is operated by the Naval Diving Unit’s Special Boat Group. The vessel is intended for time-sensitive maritime counter-terrorism operations and enables the insertion of special forces teams using the sea as cover. The CCU is a semi-submersible tactical diving vehicle believed to be based on the JFD Carrier Seal, a craft already in use with the US Navy SEALs and the United Kingdom’s Special Boat Service.
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The Combatant Craft Underwater (CCU) can be deployed from surface vessels such as Landing Platform Docks or the upcoming Multi-Role Combat Vessels, and may also be mounted behind the fin of submarines like the Type 218SG. (Picture source: RSN)

The Combatant Craft Underwater (CCU) supports covert underwater and surface missions and is intended for shallow water operations, including ship interceptions and beach landings by combat divers. The Republic of Singapore Navy (RSN) demonstrated the capabilities of its vehicle, which can be transported by various means and operated in multiple deployment modes. The platform is part of a broader effort to expand the operational flexibility of Singapore's Naval Diving Unit in support of maritime security missions.

The Naval Diving Unit (NDU) of the Singaporean Navy is the maritime special forces formation responsible for conducting operations by sea, air, and land under the command of the Special Operations Task Force. The unit was established in 1975 and comprises six distinct sub-units: the Special Warfare Group (SWG), the Special Boat Group (SBG), the Clearance Diving Group, the Underwater Demolition Group, the 180 Squadron, and the Frogman School. The Special Warfare Group, which was formed in 1989 and later integrated into the Special Operations Task Force, focuses on counter-terrorism, reconnaissance, and direct action missions. Its personnel undergo a progression of qualifications, beginning with the Combat Diver Course and followed by advanced special warfare training. The Special Boat Group is tasked with operating surface and sub-surface craft, including the recently adopted Combatant Craft Underwater, which supports shallow-water insertion and extraction of combat divers. The Clearance Diving Group and Underwater Demolition Group carry out explosive ordnance disposal, mine countermeasure activities, and demolition tasks. The 180 Squadron conducts ship boarding operations, including force protection and inspection of commercial vessels. The Frogman School is responsible for training, selection, and assessment of new personnel entering the unit.

The JFD Carrier Seal, which serves as the apparent basis for the CCU, is a Tactical Diving Vehicle (TDV) capable of operating in surface, semi-submerged, and fully submerged configurations. It measures 10.45 meters in length, 2.23 meters in beam, and 1.65 meters in height. It is designed to carry two crew members and six combat divers, along with equipment for mission-specific tasks, totaling a neutral buoyant payload of up to 1,000 kilograms. The craft weighs 4,000 kilograms. In surface mode, it is powered by a 345 horsepower water-cooled diesel engine coupled with a Kongsberg water jet, allowing for high-speed transits at up to 30 knots, with a cruise speed of 25 knots. In submerged operations, it switches to electric thrusters powered by two 20 kWh battery packs, enabling speeds over 5 knots and a cruising speed of 4 knots.

The Combatant Craft Underwater (CCU) has been presented as capable of conducting various insertion and extraction missions in littoral environments. It can be deployed from multiple host platforms, including surface vessels such as Landing Platform Docks or the upcoming Multi-Role Combat Vessels, and may also be mounted behind the fin of submarines like the Type 218SG. The CCU can be transported in a 40-foot ISO container and launched from a harbor slipway using a dedicated trailer. It can also be airdropped using the SEAL Air Delivery System, which includes an aluminum transport frame and a clustered-canopy parachute deployment method. When deployed, the craft has a surface range of 150 nautical miles, extendable by 75 additional nautical miles with auxiliary fuel bags. Its submerged range is 15 nautical miles, which can also be doubled to 30 nautical miles by fitting extra battery packs.

The platform's roles include delivery of six-person combat teams to shorelines, interception of commercial vessels, harbor patrol, and rapid-response in anti-piracy missions. Additional uses include mine countermeasures and surveillance operations. The CCU incorporates a built-in diver breathing system that permits extended submerged operations. The tactical mast is height-adjustable and fitted with thermal imaging, a color TV camera, navigation lights, and a GPS antenna. Its Steering Information Navigation and Control (SINC) system integrates data from GPS, a depth sounder, Obstacle Avoidance Sonar, Doppler Velocity Log, and gyro compass to facilitate accurate navigation in both surface and submerged modes.

The internal configuration places the driver and commander at the front instrument panels, with the six divers seated behind them inside the hull. Quick access panels enable rapid entry and exit. The craft’s structure includes mounting points for optional systems such as side-scan sonar, communication equipment, Remotely Operated Vehicles (ROVs), Autonomous Underwater Vehicles (AUVs), and various weapon systems. It can carry ammunition, explosives, survival gear, and sensor equipment, enabling the craft to support multiple mission types. The CCU can also be towed by a surface vessel at 30 knots or launched and recovered using cranes, A-frames, davits, or moon pool arrangements, depending on the configuration of the host platform.

Statements from official and defense observers have emphasized that while diver propulsion devices and smaller swimmer delivery vehicles are common in naval special forces units, larger semi-submersible vehicles like the CCU are comparatively rare due to higher acquisition and integration costs. The Singaporean Navy has now joined other operators of such systems by fielding this vehicle. The CCU is designed for below-the-horizon operations in contested or low-visibility maritime environments and is aligned with broader regional developments in maritime special operations capabilities. Social media posts from JFD and Singapore-based defense channels have documented the RSN’s public demonstration of the platform and its role in a joint capabilities event that followed a US Special Operations Command demonstration.

The CCU is capable of fulfilling a wide variety of tactical roles beyond traditional diver delivery. It can host sensors and weapons, navigate independently using integrated positioning tools, and operate effectively in both coastal and offshore environments. The platform has been designed to be logistically mobile, operationally adaptable, and suitable for both peacetime security missions and contingency operations requiring stealth and low detection probability. The combination of surface speed, submerged endurance, and multi-mode deployment options reflects a platform optimized for littoral operations where conventional vessels or diver delivery methods may be insufficient. The incorporation of systems previously only fielded by NATO special operations forces into the Singaporean Navy’s inventory suggests a continued shift towards high-value, multi-role maritime special operations capabilities.