(covers information from several alternate timelines)
A submarine was a type of specialized watercraft that could operate underwater, which was employed by several Earth navies and other operators.
Malcolm Reed's great-uncle was a member of the submarine arm of the Royal Navy. As chief engineer he served aboard HMS Clement, a nuclear powered submarine. Reed's great-uncle died after the submarine struck a mine, giving his life to help the rest of the crew reach the escape pods by keeping the reactor online long enough. (ENT: "Minefield")
Upon seeing Monean research vessels break through the surface of The Waters and travel through space, Tom Paris wondered in 2375 whether those vessels were "starships or submarines." (VOY: "Thirty Days")
|aircraft carrier • barge • boat • brig • clipper ship • destroyer • felucca • ferryboat • fireboat • fishing boat • galleon • gondola • hydroscoot • hydro-skimmer • ice-cutter • ironclad • nuclear vessel • ocean-going vessel • passenger liner • pulse-rigger • raft • rowboat • sailboat • sailing ship • scouter-gig • slave ship • steamship • submarine • surfboard • war galley • whaling ship • yacht|
In TOS: "Balance of Terror", a Romulan Bird-of-Prey, equipped with a cloaking device, metaphorically represents a submarine, hiding from and combating the USS Enterprise, which represents an opposing vessel on the surface of a stretch of water. In effect, two submarine war movies, The Enemy Below and Run Silent, Run Deep, served as the basis for the episode's plot. Also, the cramped bridge of the Bird-of-Prey was deliberately evocative of a submarine, and it even included a periscope-like scope. (The Star Trek Compendium, 4th ed., p. 40)
The sets of the USS Defiant and Enterprise NX-01 were designed to be reminiscent of submarine interiors. In the former's case, one episode in particular, DS9: "Starship Down", was intentionally reminiscent of well-known submarine movies such as Das Boot.
The images from the opening credits of "In a Mirror, Darkly" were recycled footage from the 1990 Paramount Pictures espionage movie The Hunt for Red October (the studio models for which, including that of the Alfa-class, built by Gregory Jein, Inc., subcontracted by Boss Film Studios. ), and the 2000 Universal Studios war movie U-571; depicted were a Soviet Alfa-class, aka Project 705, and a German Type VII submarine, the most ubiquitous type used by the German Kriegsmarine in World War II.