A SEAL Delivery Team member climbs aboard a delivery vehicle before launching from the back of the submarine USS Philadelphia.

A frogman is someone who is trained in scuba diving or swimming underwater in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, combatant diver, or combat swimmer. The word frogman first arose in the stage name the "Fearless Frogman" of Paul Boyton in the 1870s[1] and later was claimed by John Spence, an enlisted member of the U.S. Navy and member of the OSS Maritime Unit, to have been applied to him while he was training in a green waterproof suit.[2]

The term frogman is occasionally used to refer to a civilian scuba diver. Some sport diving clubs include the word frogmen in their names.[citation needed] The preferred term by scuba users is diver,[citation needed] but the frogman epithet persists in informal usage by non-divers, especially in the media and often refers to professional scuba divers, such as in a police diving role.[3]

In the U.S. military and intelligence community, divers trained in scuba or CCUBA who deploy for tactical assault missions are called "combat divers".[citation needed] This term is used to commonly refer to Navy UDTs, Navy SEALs, Navy SARC, and the Navy Explosive Ordnance Disposal (EOD) units. Navy SWCC have frogmen heritage of combat swimming rather than diving, one of the few and most elite units trained in this element. Other frogmen units include marine raiders marine recon, elements of US Army Special Forces (aka Green Berets) combat divers, Army Rangers Regimental Reconnaissance Company, Air Force Pararescue, Air Force Combat Controllers, and Air Force Special Reconnaissance, as well as operatives of the CIA's Special Activities Center.

In the United Kingdom, police divers have often been called "police frogmen".[4]

Some countries' tactical diver organizations include a translation of the word frogman in their official names, e.g., Denmark's Frømandskorpset; others call themselves "combat divers" or similar. Others call themselves by indefinite names such as "special group 13" and "special operations unit".[citation needed]

Many nations and some irregular armed groups deploy or have deployed combat swimmers or divers. [citation needed]

Scope of operations

Tactical diving is a branch of professional diving carried out by armed forces and tactical units. They may be divided into:[citation needed]

These groups may overlap, and the same men may serve as assault divers and work divers, such as the Australian Clearance Diving Branch (RAN).

The range of operations performed by these operatives includes:[citation needed]

Typically, a diver with closed circuit oxygen rebreathing equipment will stay within a depth limit of 20 feet (6.1 m) with limited deeper excursions to a maximum of 50 feet (15 m) because of the risk of seizure due to acute oxygen toxicity.[5] The use of nitrox or mixed gas rebreathers can extend this depth range considerably, but this may be beyond the scope of operations, depending on the unit.

Mission descriptions

US and UK forces use these official definitions for mission descriptors:[citation needed]

keeping out of sight (e.g., underwater) when approaching the target.[citation needed]
carrying out an action of which the enemy may become aware, but whose perpetrator cannot easily be discovered or apprehended. Covert action often involves military force which cannot be hidden once it has happened. Stealth on approach, and frequently on departure, may be used.[citation needed]
it is intended that the enemy does not find out then or afterwards that the action has happened – for example, installing eavesdropping devices. Approach, installing the devices, and departure are all to be kept from the knowledge of the enemy. If the operation or its purpose is exposed, then the actor will usually make sure that the action at least remains "covert", or unattributable.[This quote needs a citation]

Defending against frogmen

Main article: Defense against swimmer incursions

Anti-frogman techniques are security methods developed to protect watercraft, ports and installations, and other sensitive resources both in or nearby vulnerable waterways from potential threats or intrusions by frogmen.


Frogmen on clandestine operations use rebreathers, as the bubbles released by open-circuit scuba would reveal them to surface lookouts and make a noise which hydrophones could easily detect.[citation needed]

Origins of the name

A few different explanations have been given for the origin of the term frogman.


See also: Timeline of underwater technology

A 1945 British navy frogman with complete gear, including the Davis apparatus, a rebreather originally conceived in 1910 by Robert Davis as an emergency submarine escape set.

In ancient Roman and Greek times, there were instances of men swimming or diving for combat, sometimes using a hollow plant stem or a long bone as a snorkel. Diving with snorkel is mentioned by Aristotle (4th century BC).[6] The earliest descriptions of frogmen in war are found in Thucydides' History of the Peloponnesian War. The first instance was in 425 BC, when the Athenian fleet besieged the Spartans on the small island of Sphacteria. The Spartans managed to get supplies from the mainland by underwater swimmers towing submerged sacks of supplies. In another incident of the same war, in 415 BC, the Athenians used combat divers in the port of Syracuse, Sicily. The Syracuseans had planted vertical wooden poles in the bottom around their port, to prevent the Athenian triremes from entering. The poles were submerged, not visible above the sea level. The Athenians used various means to cut these obstacles, including divers with saws.[7] It is believed that the underwater sawing required snorkels for breathing and diving weights to keep the divers stable.[8]

Also, in the writings of Al-Maqrizi, it is also claimed that the naval forces of the Fatimid Caliphate, in an engagement with Byzantine forces off the coast of Messina henceforth referred to as the Battle of the Straits, employed a novel strategy with strong similarities to modern-day frogmen tactics. In the writings of Heinz Halm, who studied and translated the writings of Al-Maqrizi and other contemporary Islamic historians, it is described: "They would dive from their own ship and swim over to the enemy ship; they would fasten ropes to its rudder, along which earthenware pots containing Greek fire were then made to slide over to the enemy ship, and shattered on the sternpost." Apparently, this tactic succeeded in destroying many Byzantine vessels, and the battle ended in a major Fatimid victory; according to the Arab historians, a thousand prisoners were taken, including the Byzantine admiral, Niketas, with many of his officers, as well as a heavy Indian sword which bore an inscription indicating that it had once belonged to Muhammad.

The Hungarian Chronicon Pictum claims that Henry III's 1052 invasion of Hungary was defeated by a skillful diver who sabotaged Henry's supply fleet. The unexpected sinking of the ships is confirmed by German chronicles.[citation needed] On 4 November 1918, during World War I, Italian frogmen sunk the Austro-Hungarian ship Viribus Unitis.

Italy started World War II with a commando frogman force already trained. Britain, Germany, the United States, and the Soviet Union started commando frogman forces during World War II.[citation needed]

First frogmen

The word frogman appeared first in the stage name The Fearless Frogman of Paul Boyton, who since the 1870s broke records in long distance swimming to demonstrate a newly invented rubber immersion suit, with an inflated hood.[1]

The first modern frogmen were the World War II Italian commando frogmen of Decima Flottiglia MAS (now "ComSubIn": Comando Raggruppamento Subacquei e Incursori Teseo Tesei) which formed in 1938 and was first in action in 1940. Originally these divers were called "Uomini Gamma" because they were members of the top secret special unit called "Gruppo Gamma", which originated from the kind of Pirelli rubber skin-suit[9] nicknamed muta gamma used by these divers. Later they were nicknamed "Uomini Rana," Italian for "frog men", because of an underwater swimming frog kick style, similar to that of frogs, or because their fins looked like frog's feet.[10][verification needed][need quotation to verify]

This special corps used an early oxygen rebreather scuba set, the Auto Respiratore ad Ossigeno (A.R.O), a development of the Dräger oxygen self-contained breathing apparatus designed for the mining industry and of the Davis Submerged Escape Apparatus made by Siebe, Gorman & Co and by Bergomi, designed for escaping from sunken submarines. This was used from about 1920 for spearfishing by Italian sport divers, modified and adapted by the Italian navy engineers for safe underwater use and built by Pirelli and SALVAS from about 1933, and so became a precursor of the modern diving rebreather.[11][12]

For this new way of underwater diving, the Italian frogmen trained in La Spezia, Liguria, using the newly available Genoese free diving spearfishing equipment; diving mask, snorkel, swimfins, and rubber dry suit, the first specially made diving watch (the luminescent Panerai), and the new A.R.O. scuba unit.[13] This was a revolutionary alternative way to dive, and the start of the transition from the usual heavy underwater diving equipment of the hard hat divers which had been in general use since the 18th century, to self-contained divers, free of being tethered by an air line and rope connection.[citation needed]

Wartime operations

After Italy declared war, the Decima Flottiglia MAS (Xª MAS) attempted several frogmen attacks on British naval bases in the Mediterranean between June 1940 and July 1941, but none were successful, because of equipment failure or early detection by British forces. On September 10, 1941, eight Xª MAS frogmen were inserted by submarine close to the British harbour at Gibraltar, where using human torpedoes to penetrate the defences, sank three merchant ships before escaping through neutral Spain. An even more successful attack, the Raid on Alexandria, was mounted on 19 December on the harbour at Alexandria, again using human torpedoes. The raid resulted in disabling the battleships HMS Queen Elizabeth and HMS Valiant together with a destroyer and an oil tanker, but all six frogmen were captured.[14] Frogmen were deployed by stealth in Algeciras, Spain, from where they launched a number of limpet-mine attacks on Allied shipping at anchor off Gibraltar.[15] Some time later they refitted the interned Italian tanker Olterra as a mothership for human torpedoes, carrying out three assaults on ships at Gibraltar between late 1942 and early 1943, sinking six of them.[16][17]

Nazi Germany raised a number of frogmen units under the auspices of both the Kriegsmarine and the Abwehr, often relying on Italian expertise and equipment. In June 1944, a K-Verband frogman unit failed to destroy the bridge at Bénouville, now known as Pegasus Bridge, during the Battle of Normandy. In March 1945, a frogman squad from the Brandenburgers was deployed from their base in Venice to destroy the Ludendorff Bridge over the Rhine which had been captured by the US Army in the Battle of Remagen. Seven frogmen swam 17 kilometres (11 mi) downriver to the bridge carrying explosives, but were spotted by Canal Defence Lights. Four died, two from hypothermia, and the rest were captured.[18]

The British Royal Navy had captured an Italian human torpedo during a failed attack on Malta; they developed a copy called the Chariot and formed a unit called the Experimental Submarine Flotilla, which later merged with the Special Boat Service. A number of Chariot operations were attempted, most notably Operation Title in October 1942, an attack on the German battleship Tirpitz, which had to be abandoned when a storm hit the fishing boat which was towing the Chariots into position.[19] Operation Principal in January 1943 was an attack by eight Chariots on La Maddalena and Palermo harbours; although all the Chariots were lost, the new Italian cruiser Ulpio Traiano was sunk.[20] The last and most successful British operation resulted in sinking two liners in Phuket harbour in Thailand in October 1944.[21] Royal Navy divers did not use fins until December 1942.[citation needed]

Wartime developments

In 1933 Italian companies were already producing underwater oxygen rebreathers, but the first diving set known as SCUBA was invented in 1939[22] by Christian Lambertsen, who originally called it the Lambertsen Amphibious Respirator Unit (LARU)[23] and patented it in 1940.[24] He later renamed it the Self Contained Underwater Breathing Apparatus, which, contracted to SCUBA, eventually became the generic term for both open circuit and rebreather autonomous underwater breathing equipment.

Lambertsen demonstrated it to the Office of Strategic Services (OSS) (after already being rejected by the U.S. Navy) in a pool at a hotel in Washington D.C.[25] OSS not only bought into the concept, they hired Lambertsen to lead the program and build up the dive element of their maritime unit.[25] The OSS was the predecessor of the Central Intelligence Agency; the maritime element still exists inside the CIA's Special Activities Division.[26]

John Spence, an enlisted member of the U.S. Navy, was the first man selected to join the OSS group.[2]

Postwar operations

In April 1956, Commander Lionel Crabb, a wartime pioneer of Royal Navy combat diving, disappeared during a covert inspection of the hull of the Soviet Navy Sverdlov-class cruiser, Ordzhonikidze, while she was moored in Portsmouth Harbour.[27]

The Shayetet 13 commandos of the Israeli Navy have carried out a number of underwater raids on harbors. They were initially trained by veterans of Xª MAS and used Italian equipment.[28] As part of Operation Raviv in 1969, eight frogmen used two human torpedoes to enter Ras Sadat naval base near Suez, where they destroyed two motor torpedo boats with mines.[29]

During the 1982 Falklands War, the Argentinian Naval Intelligence Service planned an attack on British warships at Gibraltar. Code named Operation Algeciras, three frogmen, recruited from a former anti-government insurgent group, were to plant mines on the ships' hulls. The operation was abandoned when the divers were arrested by Spanish police and deported.[30]

In 1985, the French nuclear weapons tests at Moruroa in the Pacific Ocean was being contested by environmental protesters led by the Greenpeace campaign ship, Rainbow Warrior. The Action Division of the French Directorate-General for External Security devised a plan to sink the Rainbow Warrior while it was berthed in harbor at Auckland in New Zealand. Two divers from the Division posed as tourists and attached two limpet mines to the ship's hull; the resulting explosion sank the ship and killed a Netherlands citizen on board. Two agents from the team, but not the divers, were arrested by the New Zealand Police and later convicted of manslaughter. The French government finally admitted responsibility two months later.[31]

In the U.S. Navy, frogmen were officially phased out in 1983 and all active duty frogmen were transferred to SEAL units. In 1989, during the U.S. invasion of Panama, a team of four U.S. Navy SEALs using rebreathers conducted a combat swimmer attack on the Presidente Porras, a gunboat and yacht belonging to Manuel Noriega. The commandos attached explosives to the vessel as it was tied to a pier in the Panama Canal, escaping only after being attacked with grenades.[32] Three years later during Operation Restore Hope, members of SEAL Team One swam to shore in Somalia to measure beach composition, water depth, and shore gradient ahead of a Marine landing. The mission resulted in several of the SEALs becoming ill as Somalia's waters were contaminated with raw sewage.[33]

In 1978, the U.S. Navy Special Operations Officer (1140) community was established by combining Explosive Ordnance Disposal (EOD) and Expendable Ordnance Management officers with Diving and Salvage officers. Special Ops Officers would become qualified in at lease two functional areas - normally EOD or Diving and Salvage, and Expendable Ordnance management. Officers trained in diving and salvage techniques were now allowed to follow a career pattern that took advantage of their training, and Unrestricted line officers were now permitted to specialize in salvage, with repeat tours of duty, and advanced training. Career patterns were developed to ensure that officers assigned to command were seasoned in salvage operations and well qualified in the technical aspects of their trade. "The combination gave a breadth and depth of professionalism to Navy salvage that had not been possible before."[34]


See also


  1. ^ a b c Kehoe, Pat (2020-08-29). "Paul Boyton - Fearless Frogman from Co Kildare". Ireland Calling. Retrieved 2021-06-09.
  2. ^ a b c Perry, Tony (2013-11-03). "John Spence dies at 95; Navy diver and pioneering WWII 'frogman'". Los Angeles Times. Retrieved 2013-11-27.
  3. ^ "The hidden world of police divers". 2010-06-14. Retrieved 2023-03-07.
  4. ^ "APPENDIX'D' Relationship between the Police and the Schools". www.gov.scot. Retrieved 2023-03-07.
  5. ^ US Navy (2006). "19". US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. p. 13. Archived from the original on 2008-05-02. Retrieved 2008-06-15.
  6. ^ Aristotle, On the Parts of Animals, ii, 16, transl. by W.Ogle, London, 1882, p. 51:
    "Just then as divers are sometimes provided with instruments for respiration, through which they can draw air from above the water, and thus may remain for a long time under the sea, so also have elephants been furnished by nature with their lengthened nostril, and, whenever they have to traverse the water, they lift this up above the surface and breathe through it."
  7. ^ Thukydides, History of the Peloponnesian War, edition Ambrosio Firmin Didot, Paris, 1842, book 4, 26, and b. 7, 25. In Greek and Latin.
  8. ^ Pierros D. Nick, The tactics of the enemies in the sea warfare during the Peloponnesian War. 1st Pan-Corinthian Congress, Corinth, Greece, 2008. In Greek. N. Pierros is a Civil Engineer and author of historical essays.
  9. ^ "Pirelli Diving Suit". www.therebreathersite.nl. Retrieved 2021-03-17.
  10. ^ Manuale Federale di Immersione - author Duilio Marcante
  11. ^ Marí, Alejandro Sergio. "Pirelli ARO WW II". Therebreathersite.nl (Janwillem Bech).
  12. ^ "Rebreathers - Rebreather Autorespiratori per l'Immersione Subacquea a recupero di gas". Archived from the original on 2012-07-10.
  13. ^ "Libri. Teseo Tesei e gli Assaltatori della Regia Marina, di Gianni Bianchi". December 13, 2005. Archived from the original on Oct 2, 2011. Retrieved Sep 3, 2022.
  14. ^ O'Hara, Vincent P.; Cernuschi, Enrico. "Frogmen against a fleet: The Italian Attack on Alexandria 18/19 December 1941". www.usnwc.edu. Naval War College Review. Archived from the original on 12 February 2017. Retrieved 19 September 2016.
  15. ^ Borghese, Valerio (1995). Sea Devils: Italian Navy Commandos in World War II. Naval Institute Press. pp. 208–09. ISBN 1-55750-072-X.
  16. ^ Borghese (1995), pp. 242-43
  17. ^ Borghese (1995), pp. 257-59
  18. ^ Blocksdorf, Helmut (2008). Hitler's Secret Commandos: Operations of the K-Verband. Barnsley, South Yorkshire: Pen & Sword Military. ISBN 978-1844157839.
  19. ^ "Information sheet no 101 - Attack on the Tirpitz" (PDF). www.nmrn-portsmouth.org.uk. National Museum of the Royal Navy. 2014. Retrieved 26 September 2016.
  20. ^ Chant, Christoper. "Operation Principal (iii)". codenames.info. Retrieved 24 May 2023.
  21. ^ Hood, Jean, ed. (2007). Submarine. Conway Maritime. pp. 505–506. ISBN 978-1-84486-090-6.
  22. ^ Downey, Sally A. (2011-02-21). "Christian J. Lambertsen, 93, developer of the first scuba gear". The Philadelphia Inquirer. Retrieved 2021-06-09.
  23. ^ Shapiro, T Rees (18 February 2011). "Christian J. Lambertsen, OSS officer who created early scuba device, dies at 93". Washington Post. Retrieved 16 May 2011.
  24. ^ "Lambertsen's patent in Google Patents". Retrieved Sep 3, 2022.
  25. ^ a b Shapiro, T. Rees (2011-02-19). "Christian J. Lambertsen, OSS officer who created early scuba device, dies at 93". The Washington Post.
  26. ^ "CIA Special Operations Group | Special Activities Division". cia.americanspecialops.com. Retrieved Sep 3, 2022.
  27. ^ Hoole, Rob (2007). "The Buster Crabb Enigma". mcdoa.org.uk. Minewarfare & Clearance Diving Officers' Association. Retrieved 21 July 2017.
  28. ^ Isseroff, Ami (2005). "Zionism and Israel - Encyclopedic Dictionary - Shayetet 13". www.zionism-israel.com. Retrieved 12 March 2017.
  29. ^ Gawrych, George Walter (2000). The Albatross of Decisive Victory: War and Policy Between Egypt and Israel in the 1967 and 1973 Arab-Israeli Wars. Praeger. p. 111. ISBN 978-0313313028.
  30. ^ "Operation Algeciras: How Argentina planned to attack Gibraltar". newhistories.group.shef.ac.uk. New Histories. 21 May 2011. Retrieved 12 March 2017.
  31. ^ Reports of International Arbitral Awards : Case concerning the differences between New Zealand and France arising from the Rainbow Warrior affair (PDF). United Nations. 6 July 1986. p. 200. Retrieved 12 March 2017.
  32. ^ Hoyt, Edwin P. (15 June 2011). SEALs at War. Random House Publishing Group. pp. 159–. ISBN 978-0-307-57006-2.
  33. ^ Mann, Don (5 August 2014). How to Become a Navy SEAL: Everything You Need to Know to Become a Member of the US Navy's Elite Force. Skyhorse Publishing. pp. 18–. ISBN 978-1-62873-487-4.
  34. ^ url=https://apps.dtic.mil/sti/citations/ADA278438

Further reading