Military Diving: The Evolution of Combat Swimmers

The Italians Who Started It

The origins of modern military diving trace to a single unit: the Decima Flottiglia MAS — the 10th Assault Vehicle Flotilla of the Italian Royal Navy, active 1940-1943. The unit's primary weapon was the Siluro a Lenta Corsa (SLC), popularly called the maiale (pig) — a two-man human torpedo on which frogmen rode in wet-suits and closed-circuit oxygen rebreathers.

On the night of 18-19 December 1941, six operators of the Decima MAS navigated their maiali through the defensive nets of Alexandria Harbour in Egypt, the main anchorage of the British Mediterranean Fleet. They attached limpet mines to the hulls of HMS Queen Elizabeth (35,000 tons), HMS Valiant (32,000 tons), and the tanker Sagona. All three ships sank or were severely damaged. This attack established frogmen as a legitimate military capability. Every major navy began developing underwater combat swimmer programs immediately.

The British Response: SBS

Britain's Special Boat Section (later Service, now Squadron) developed in parallel with the Italian program. By 1944, the SBS incorporated underwater demolition techniques using hard-hat diving equipment for harbour clearance and obstacle removal.

The Combined Operations Assault Pilotage Parties (COPP) conducted underwater reconnaissance of potential invasion beaches before D-Day, swimming in to measure beach gradients, locate obstacles, and retrieve sediment samples.

US Navy Underwater Demolition Teams

America's answer was the Underwater Demolition Teams (UDTs), formed in 1943 from experience at the disastrous beach-obstacle encounters at Tarawa and Normandy. UDT operators swam to beaches before amphibious landings, neutralized obstacles, and mapped approach routes — initially without scuba, holding their breath and wearing only swim trunks, fins, and a face mask.

After the war, UDT teams adopted scuba equipment and evolved into the US Navy SEALs — established by President Kennedy in January 1962.

Cold War Developments

The Cold War drove underwater technology in several military directions:

• Rebreather refinement: Closed-circuit oxygen and mixed-gas rebreathers were standard military equipment decades before recreational use. The lack of bubbles was operationally essential.
• Swimmer Delivery Vehicles (SDVs): Small, flooded submersibles allowing combat swimmers to reach targets without fatigue. The US SEAL Delivery Vehicle Team operates the Mark 8 SDV and the Dry Combat Submersible (DCS).
• Mine countermeasures: Most navies maintain specialized mine clearance diving units.

Modern Applications

Today's military diving encompasses: harbour and ship hull inspection; underwater demolition and explosive ordnance disposal; beach and waterway reconnaissance; infrastructure protection; and Special Operations maritime infiltration. NATO maintains standardized combat diver qualification standards. The French Marine Nationale Commando Hubert, the British SBS, the German KSK, and the Israeli Shayetet 13 are among the most capable units.