The Evolution of US Combat Diving. Part 1, the Early History.

Exploring the evolution of combat diving.

This is Part 1 of 7 taken from my Submarine Medical Officer Thesis “A Review of the Combat Diving Evolution of US Naval Special Warfare with a Focus on the Necessity of Disruptive Technologies and Innovative Scientists.” Stay tuned for part 2 next week.

Abstract. The process of innovative scientists creating disruptive technologies for adaptive warriors has historically played a critical role in the evolution of Naval Special Warfare (NSW), and will continue to be critical to the future development and successful employment of NSW forces. Despite initial resistance followed by gradual acceptance, it was only as NSW embraced and fully exploited novel combat diving technologies and capabilities that the UDT/SEALs became fully operational maritime warriors.

This study will review the evolution of US Navy combat diving and examine the creation and integration of three critical diving related technologies – the closed-circuit “re-breather,” the swimmer delivery vehicle, and the dry deck shelter – and how these innovations not only offered additional capabilities to NSW, but also shaped and will continue to shape the evolution of the US Navy combat diving program.

The Early History of Combat Diving

The United States Navy SEALs are the premier maritime special operations force (SOF) of the most powerful military in the world, and although they were officially created in 1962, their inception dates back to Word War II (WWII) and the terrible beaches of a tiny atoll known as Tarawa.

“Terrible Tarawa.” On November 20, 1943, Marine forces invaded the tiny Tarawa Atoll (Fig. 1) in what was supposed to be an easy defeat early in the campaign of “island hopping” toward Japan. Preparations made prior to the invasion included aerial photography, submarine sounding and reconnaissance, interviews with the locals, and finally a massive bombardment that was promised to obliterate the resistance. Unfortunately, due to an unforeseen change in tides, only the first wave of Marines made it ashore, with the second and subsequent waves becoming stranded on the shallow coral reef surrounding Tarawa. The second wave disembarked from the stranded landing craft only to drown or be decimated in large numbers by a stiff resistance that had survived the preparatory bombardment.1,2

Three days later, the tiny island was overtaken, but only after heavy American losses with more than a thousand dead and another two thousand wounded. Despite seemingly thorough preparations, the US commanders failed to send preliminary reconnaissance personnel ahead to “get hands on”, scout the beaches, find channels through the reefs, and destroy natural and man-made obstacles obstructing the path of the main assaulting amphibious force. This basic oversight3 and resulting tragedy prompted the amphibious fleet commander, Rear Admiral (RADM) Richmond Turner, to demand that special teams trained in beach reconnaissance and demolition integrate with the marine amphibious forces for the pending dash across the Pacific.4,5

Figure 1: Map of Day 2 at 1800 on Bititu Island of the Tarawa Atoll.6

The NCDU. The capabilities that RADM Turner requested actually already existed in the newly created Navy Combat Demolition Unit (NCDU). The NCDU, created earlier that year, recruited its members primarily from the “Seabees”7 and from the “Scouts and Raiders.”8,9,10,11 After successfully completing an ad hoc, arduous training program at Fort Pierce, Florida, Navy Combat Demolition Teams (NCDTs) deployed to Europe and were the first men on the beach at Normandy in 1944 to clear the way for the massive Allied amphibious invasion. Despite the austere environment, minimal equipment, and limited time, the NCDTs successfully cleared lanes sufficient for the invasion force to reach the shore and establish a beachhead uninhibited by obstacles, unlike what happened at “Terrible Tarawa.”12,13

The UDTs. Eventually, most of the NCDTs were absorbed into the Underwater Demolition Teams (UDTs). The UDTs were created in the Pacific immediately after Tarawa at the urging of ADM Nimitz and through the workings of RADM Turner. UDT 1 and UDT 2 were formed initially and were composed mostly of the Pacific NCDTs, along with some Seabees, Marines, and a few members of the Army. Shortly after their creation, nearly 200 men were instructed in the UDT art at Waimanolo, Oahu, and became operationally active within two months.14 The UDTs grew in numbers, matured, and participated in nearly every amphibious operation throughout the remainder of WWII.15 They offered a unique, valuable skillset to amphibious commanders that ensured the UDTs’ survival after WWII. With the waning war, short-sighted, conventionally minded military commanders decommissioned all US SOF except for a few of the UDTs who eventually established commands in San Diego, California; and Little Creek, Virginia.16

In the early 1950s, the UDTs operated in the Korean War, but for the first time in their short history, they infiltrated beyond the beaches into enemy territory and utilized their demolition skills to destroy enemy railways, bridges, tunnels, and other structures.17 They independently expanded their role to involve capabilities never originally intended, but subsequently secured their future with the impending impetus to further develop SOF.18,19

The SEALs. When John F. Kennedy (JFK) assumed the presidency of the United States in 1961, he recognized that the conventional “Cold War” mindset no longer addressed the changing nature of warfare and the rising insurgent “limited” wars. He changed American defense policy from the “mass retaliation” concept implemented by President Eisenhower to a more conducive “flexible response” that addressed the threat of Communist insurgencies. One result of this effort was the expansion of SOF throughout the military and the creation of the SEAL (Sea-Air-Land) Teams in 1962, which was actually more of a ratification of the new missions explored by the UDTs in the Korean War. Initially, the UDTs operated from the ocean to the high water mark specializing primarily in the maritime environment, while the SEALs operated from the high water mark inland specializing primarily in land warfare.20,21

During this politically and organizationally revolutionary period, the UDTs were experimenting with an equally revolutionary technology – the closed-circuit underwater breathing apparatus (UBA) – that would transform their effectiveness in combat by expanding their capabilities in the maritime environment.

Continued in Part 2…


  1. Orr Kelly, Brave Men Dark Waters: The Untold Story of the Navy SEALs (Novato, CA: Presidio, 1992), 5-7.
  2. Kevin Dockery, Navy SEALs: A Complete History from World War II to the Present (New York: Penguin, 2004), 44-45.
  3. Orr Kelly, Never Fight Fair: Navy SEALs’ Stories of Combat and Adventure (Novato, CA: Presidio, 1995), 224.
  4. Kelly, Brave Men, 5-7
  5. Dockery, Complete History, 44-45.
  6. “Intelligence Map Bititu (Betio) Island, Tarawa Atoll, Gilbert Islands,” picture from Wikipedia, accessed December 19, 2015,
  7. Derived from “CBs” for Construction Battalions. The Seabees were Navy construction and demolition experts.
  8. “S&R units” were early amphibious commandos active in Operation TORCH in Northern Africa in 1942-43.
  9. Kelly, Brave Men, 7, 10, 17-18
  10. Dockery, Complete History, 11-18
  11. Tim Bosiljevac, SEALS: UDT/SEAL Operations in Vietnam. (Boulder, CO: Paladin Press, 1990), 2.
  12. David Jordan, The U.S. Navy SEALs (New York: Sterling Publishing, 2012), 11-15
  13. Dockery, Complete History, 56-59.
  14. Dockery, Complete History, 44-47.
  15. Bosiljevac, SEALS, 3.
  16. Dockery, Complete History, 137-138.
  17. Bosiljevac, SEALS, 5
  18. Kelly, Brave Men, 70-73
  19. David Tucker and Christopher J. Lamb, United States Special Operations Forces (New York: Columbia University Press, 2007), 79, 89-90.
  20. Dockery, Complete History, 578
  21. Tucker and Lamb, Special Operations Forces, 88-90.

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