In the ''long'' history (at least back to 1775) and ''considerable'' number (more than 2000) of submarines used in warfare... how many times do you think a submerged submarine has sunk another submerged submarine? 500? 200? 100? 50? 10?

Actually, to the best of our knowledge it has happened just once, during Operation Caesar, when HMS ''Venturer'' sank ''U-864''.[[note]] Thankfully, since ''U-864'' was transporting several types of industrial {{Unobtanium}}, advanced vehicle blueprints, and technical experts (back) to Japan.[[/note]] A second example, lacking citation, may have involved the captured German U-Boat later re-launched as HMS ''Morse''.[[note]] The ''Morse'' was used by the Royal Navy to patrol the sea lanes leading back to the German home bases in western France, the intention being for returning German U-Boats, relaxing security on the last stage home, to see nothing more than a friendly submarine - which would then run up the White Ensign and fire a spread of torpedoes at them. The ''Morse'' sank several U-Boats in surface attacks and ''may'' have sunk one that was submerged.[[/note]]

But if you were to believe Hollywood, it's a regular occurrence. No matter what war, or what type of subs are involved... they will be fighting underwater.

During World War I and World War II, submarines were almost entirely ''episodically'' submersible torpedo boats, obliged to run on the surface using their air-breathing engines (mostly diesel-electric propulsion systems) for higher speed, greater endurance, and to charge the batteries that allowed them to maintain steerage and very slow speeds underwater. ''While surfaced'', submarines were just as vulnerable to torpedo attacks made by submerged enemy submarines as any other vessel, but because of their lower profiles (small conning towers, decks almost awash) were difficult to detect visually, and thus rarely attacked by enemy submarines.

Of the 52 submarines lost by the U.S. Navy in World War II, at least one - USS ''Corvina'' (SS-226) - was confirmed torpedoed and sunk by a Japanese submarine while running on the surface, while the Japanese lost five submarines to American submarine attacks. Three of the Japanese losses were credited to USS ''Batfish'' during a single three-day period in February 1945. During WWI, a US sub spotted a submerged U-boat off the southern coast of Ireland and was about to attack it when the ''U-boat'' exploded all on its own; it is surmised that the U-boat attempted to attack the US boat and its torpedo exploded in the tube.

That said, it does reflect actual military doctrine despite the sparsity of major naval conflict since World War II. This is because due to the nature of water acoustics and sonar a submarine has the best chance of successfully detecting another submarine as other real time methods are comparatively deaf. Whilst the crew of the ''Venturer'' only [[AwesomeByAnalysis had paper, pencils and decent maths skills]] to plot a firing solution, modern subs have computers and advanced homing torpedoes - had the UsefulNotes/ColdWar turned hot after the 1960s (not before then), there certainly would have been underwater submarine battles--and in fairness, that is when a large number of such sub battles are set (thank you, Creator/TomClancy!). NATO and Warsaw Pact submarines followed each other about all the time. Current American naval doctrine is to have each carrier battle group (structured around a ''Nimitz''- or ''Gerald Ford'' class supercarrier) accompanied by two [[UsefulNotes/TypesOfNavalShips nuclear attack submarines (SSN)]] which include enemy sub-killing in their tasking - these are generally known as "Hunter-Killer" submarines. In fact, it's often said that the best defense against submarines in modern warfare is your own submarines, as they can dive beneath thermocline layers that hostile subs would use to hide from surface ships[[note]] The advent of towed sonar arrays has allowed destroyers and similar ships to stream their "ears" beneath the layer, while devices like the US Navy's Prairie Masker system make them much harder to detect, closing the gap considerably. However, submarines remain inherently more stealthy than anything that stays on the surface.[[/note]]

[[AC:{{Anime}} and {{Manga}}]]
* ''Manga/Submarine707R'' (Mission 2)
* ''Manga/TheSilentService''
* ''Manga/{{Cyborg 009}}'' features a scene where the team's mobile base is being pursued separately by both an American and Soviet sub. The heroes make their getaway when the two subs notice each other and begin fighting.
* ''Anime/BlueSubmarineNo6'', although it's less sub-on-sub and more sub-on-monster-whales.
* ''LightNovel/FullMetalPanic'': The last episodes of season 1 feature the huge submarine from which the hero operate trying to and succeeding in evading an American Los Angeles class submarine captained by an officer obsessed with Mithril's mythical submarine unofficially called "Toy Box". While the Tuatha de Danaan doesn't fire a single torpedo, the Americans on the other hand do, she (and it's a definite she at that point as the "female" AI commanding it was linked to the shows resident tsundere Kaname Chidori) does get to pull some very impressive maneuvers verging on the impossible for such a huge sub, and forces the American sub to the surface.
* In ''Manga/ArpeggioOfBlueSteel'' the main characters are the crew of the submarine I-401, so there are several battles between submarines:
** I-401 manages to destroy an underwater submarine while under fire by the cruiser Takao, though to be fair I-401 used a WaveMotionGun to achieve it.
** I-401 also uses an even ''bigger'' WaveMotionGun to vaporize the tender submarine ''Milchkuh'' from over 10km away.
** In the anime, I-401 comes under torpedo attack from her sister submarines I-400 and I-402 as one of the more significant battles.

* ''Film/TheHuntForRedOctober'' is the TropeCodifier.
* ''Film/CrimsonTide'' features a skirmish between the USS ''Alabama'' and a Russian ''Akula''-class hunter-killer. The ''Akula'' is destroyed, but gets off a torpedo that damages the ''Alabama''.
* ''Film/{{U 571}}'' does this, with the Americans in the captured German U-Boat destroying another submerged German U-Boat with torpedoes.
* ''Film/GIJoeTheRiseOfCobra'' features what amounts to a dogfight [[InSpace UNDER WATER!]]
** It also features what amounts to the trench run in ''Franchise/StarWars'' Episode 4 [[InSpace UNDER WATER!]].
* ''Film/DownPeriscope'' involves a wargame that tests if a rogue UsefulNotes/WorldWarII-era diesel submarine, run by a RagtagBunchOfMisfits, is capable of outmaneuvering the US Navy and cause significant damage to major ports. The diesel's main opponent? A ''[[ Los Angeles]]'' class nuclear attack sub. The exercise included two simulated attacks on naval ports where the diesel sub is assumed to do significant damage. The first attack has a scene where the old boat surfaces and launches flares (stand-ins for actual weapons) in sight of two admirals eating dinner. The second one was where Admiral Winslow (Rip Torn) authorised the use of live torpedoes by Lt Commander Tom Dodge (Creator/KelseyGrammer) against a target hulk, in place of the flares.
** During the final chase scene, both subs surface to increase their speed. However, in RealLife, this would have only increased the ''Stingray'''s speed and would have ''slowed down'' the ''Orlando''. UsefulNotes/WorldWarII-era subs were designed to be faster on the surface. However, the cucumber shape of modern nuclear subs is best utilized underwater.
* ''Film/TheAbyss'' deserves a mention here. The minisubs involved aren't fighting with weapons- they're fighting ''over'' a weapon.
* Another particularly brutal minisub duel occurs in the Film/JamesBond film ''Film/ForYourEyesOnly''. The bad guy's sub was actually piloted by the man who designed it, Graham Hawkes, who, amusingly, tried so hard to make the fight scene realistic (having been ordered to by the director, despite his earlier protests it was unsafe) that he almost killed Creator/RogerMoore's stunt double.
* ''Film/RunSilentRunDeep'' depends on, and arguably laid the groundwork for this trope since it turns out the Japanese vessel taking out American subs in the Bungo Straits is not a surface vessel, but another submarine.
** It is torpedoed when it is lured to the surface rather than under the surface. The original writer was a submariner himself and knew perfectly well that it was pretty much impossible for one submerged submarine to torpedo another in UsefulNotes/WorldWarII.
* ''Film/InEnemyHands'' features several undersea battles with American and German submarines in the closing days of UsefulNotes/WorldWarII.

* Several of the ''Literature/JackRyan'' books give a significant focus to submarine operations, in particular ''Literature/TheHuntForRedOctober'' and ''The Sum of All Fears''.
* One of the primary plots of ''Literature/RedStormRising'' is the second Battle of the Atlantic during a non-nuclear WorldWarIII, with a significant focus on the efforts of the USS ''Chicago'' (SSN-721) and other NATO submarines against the Soviet surface and submarine fleets.
* There's a sub v. sub fight in, of all places, ZombieApocalypse novel ''Literature/WorldWarZ''. And no, neither sub was piloted by Zombies. If they were, this entry would be on the CrowningMomentOfAwesome page. The subs involved were both nuclear submarines crewed by loyalist and renegade members of the Chinese Navy as China was being torn apart by both the zombie epidemic and a civil war. [[spoiler:The renegade sub won, and then proceeded to nuke the Politburo to end the civil war]].
* ''Literature/TheDragonInTheSea'' (AKA ''Under Pressure'') by Creator/FrankHerbert depicts tense underwater combat TwentyMinutesIntoTheFuture between nuclear submarines. Despite being published in 1956 it has survived the ravages of ScienceMarchesOn and {{Zeerust}} remarkable well.
* Creator/FyodorBerezon's novel ''Incoming Cataclysm'' features an all-out battle between two modern carrier battle groups. A rip in space/time results in an entire carrier battle group crossing over from a parallel world. The ships belong to an alternate Soviet Union, which dominates much of the alternate world thanks to Operation Barbarossa being delayed by a month. Our world's US Navy decides to engage the "invaders" (who have no idea they crossed over and think they're fighting ''their'' Americans). The battle results in the loss of two supercarriers (one American and one Soviet). Since the rip was (in part) powered by the presence of active nuclear reactors, the remaining Soviet ships disappeared. However, a super-advanced Soviet nuclear submarine remained and proceeded out of the area. One of this trope's actions results when a Russian submarine decides to investigate the area and gets sunk by an American sub, which was looking for the Soviet one. When an American sub later detects the Soviet one (whose sonar is weaker), it launches torpedoes at it. The Soviets dive to a depth that is crushing for our world's submersibles but not to its enhanced hull, resulting in the torpedoes being crushed. It retaliates by launching nuclear-tipped torpedoes at the foe. The American sub manages to evade them, but the resulting pressure wave damages the boat, causing it to sink past crush depth. Both engagements are very quick.
* ''The Silent Deep: The Royal Navy Submarine Service Since 1945'' by James Jinks and Peter Hennessy notes that it is surprisingly easy for subs to crash into each other, despite having a whole ocean to play around in. Sub A learns that Sub B is nearby, and tracks it using passive sonar. Passive sonar gives good directional information, but range is little more than educated guesswork based on how much noise one expects the target to be making. If Sub B is quieter than Sub A thinks, then it is possible for Sub A to run right into it. Active sonar gives accurate range, but the ping is a dead giveaway.

* ''Series/SeaQuestDSV'', in its third season had [[RuleOfCool actual]] [[SpaceFighter ''sub fighters'']] - the Specter-class for [[TheFederation the UEO forces]], and a host of other types for various bad guys forces.
** The Chao Dai (Vietnamese) actually have the best sub-fighter pilots, since they have brain implants that jack into the sub-fighters and control the craft by thought. During the one episode they're shown, they manage to destroy one of the ''[=SeaQuest=]'' sub-fighters, piloted by a semi-regular character. She is promptly replaced by a rogue Chao Dai female pilot. Yes, they kill off one TwoferTokenMinority (a black woman) to immediately replace her with another. This was the last episode before the series was cancelled, though.
** There was also an episode where the ''[=seaQuest=]'' ended up in the past during the UsefulNotes/CubanMissileCrisis. They found out that an American submarine was positioned in the wrong place and would attack a Soviet ship because they would assume it would cross the NavalBlockade. They fire torpedoes at the ''[=seaQuest=]'', who use futuristic interceptor torpedoes to destroy them. Confused, the Americans deploy a distress beacon, which would also trigger a war. Luckily, [[HeroicDolphin Darwin]] manages to disable the beacon.
** In fact, it even happens in the ''pilot'' episode, when Bridger commands ''[=SeaQuest=]'' in an underwater duel with a submarine captained by his rogue former protege.
* Seen on ''Series/LastResort'' as the US Navy think the ''USS Colorado'' has gone rogue and is expending every effort to recapture or sink her, and the best way to do that is with attack subs.
* In the ''Series/{{Thunderbirds}}'' episode "Desperate Intruder", Thunderbird 4 engages The Hood's submarine in combat and sinks it.

* The tabletop game Captain Sonar has two teams each controlling a sub and attempting to locate and sink the opposing team.

* In the American campaign of ''VideoGame/BattlestationsPacific'', this is an AvertedTrope due to the fact that no Japanese submarines appear in the levels where American submarines are present. Played straight in the Japanese campaign though.
* ''VideoGame/AnnoDomini'' includes lots and lots of naval battles. But Anno 2070 specifically also includes submarines, courtesy of the Tech faction. Very few submarines are useful for attacking other subs while underwater, and most of your sub kills will probably come from surface ships, but is IS possible to encounter this trope in-game.
* ''VideoGame/InTheHunt'' is practically ''made'' of this about half the time. You play a sub, and you shoot down enemy subs... and planes, robots, a dragon-snail, and a LivingStatue.
* ''VideoGame/FinalFantasyVII'' has a [[UnexpectedGameplayChange minigame]] where you pilot a submarine to seek and destroy another submarine.
* ''RedFaction'' had a submarine-on-submarine section with ridiculously clear water.
** So did ''Red Faction II''. (To be fair, it also had an underwater base you needed to infiltrate.)
* The classic sub simulator ''688AttackSub'' features several Cold War-era missions that involve sub-on-sub combat.
* ''VideoGame/SubmarineTitans'', a real-time strategy game taking place underwater with subs. Combat occurs at close range, but stray torpedoes can hit targets at a distance.
* Creator/SidMeier also did a game version of ''Literature/RedStormRising'', which, like the novel mentioned above, has plenty of this.
** Completely [[AvertedTrope averted]] in the sequel, though. Japanese subs didn't even have any sprites.
** Also [[AvertedTrope averted]] in the NES version - there were no other subs. The %@&! kaiboken, on the other hand...
* VideoGame/DangerousWaters.
* Subs are reasonably effective against other subs in ''VideoGame/RiseOfNations'', though [[TacticalRockPaperScissors ultimately less effective than cruisers at the job]].
* The ''Videogame/{{Aquanox}}'' series is basically a space combat sim underwater, involves a lot of dogfights, mostly using futuristic weapons, complemented with occasional torpedo launches. Unlike actual submarines, most subs featured in the series were all single-pilot with a cockpit. In a bit of realism, there was a way to instantly kill another sub by shooting out the thin cockpit glass with a sniper-like weapon, causing the other sub to implode. Strangely though, hitting the same glass with a much more powerful weapon would not necessarily have the same effect.
* The [=PS1=] game ''VideoGame/CriticalDepth'' was basically Twisted Metal UNDERWATER. Subs ranged from a wooden pirate sub with cannons to a converted private jet. It was not very realistic.
* ''VideoGame/XCOMTerrorFromTheDeep'' had this when intercepting alien craft. Then again, all of the alien races from this installment of the X-Com series were amphibious, traveled around in weird-looking submarines, and came from a colony ship that crashed some 65 million years ago.
** Also, for the sake of completeness, the submarines in the game are ''flying'' submarines. That's right: sufficient velocity to break the surface of the water means you can activate turbo jets and fly! Weapons only work underwater though (which generally makes sense: torpedoes don't have the right engines, the powerful sonic cannon apparently has vastly decreased range when you're traveling faster than the speed of sound, and the omni-powerful Pulse Wave Torpedo actually requires water to work properly).
* ''VideoGame/SupremeCommander'' features submarines as an entry level naval unit, but due to the lack of decent anti-submarine weapons, they tend to be used in massed fleets late game. The only real counter to these fleets are more submarines as destroyers(the anti-submarine boat) are simply too expensive to produce in large numbers and torpedo bombers (the anti-submarine aircraft) are vulnerable to anti-aircraft surface fire.
** The ''Forged Alliance'' expansion pack adds submarine hunters for each of the factions as a counter to this. The submarine hunters tend to be effective against against submerged targets but are vulnerable to to surface warships.
* ''[[NavalOps Warship Gunner 2]]'' allows you to engage enemy subs underwater if you're controlling a submarine. Note that you are completely PointDefenseless while submerged and submarines usually attack with torpedoes. If you'd researched the best sonar and long-range torpedoes (giving yourself superior detection and attack range to enemy subs), you'd be fine as long as you didn't advance too quickly. If you didn't do that, expect to see the game over screen frequently.
* Pretty much averted in ''Videogame/WarcraftII''. Submarines and sea turtles must surface to fire and can only be fired upon if a flying unit (griffon, dragon, helicopter, or zeppelin), tower or another sub or sea turtle can see them.
* In ''VideoGame/CommandAndConquerRedAlert2: Yuri's Revenge'', the Soviets and Yuri's forces have submarines, except a fight between them involves floating in place while shooting one torpedo after another until either is destroyed. The Allies only have surface ships and trained [[HeroicDolphin dolphins]].
** ''[[VideoGame/CommandAndConquerRedAlert3 Red Alert 3]]'' gives Akula submarines to the Soviets and smaller Yari mini-subs which can perform kamikaze attacks to the Empire. The Imperial Sea-Wing is also underwater, but doesn't count because it is anti-air only in that state. The Allies are again left with dolphins.
* The old Origin game Subwars 2050 was an action/simulator of submarine combat where submarines are purposely built with aerodynamic, jetfighter-like hulls for better maneuverability. Oddly in-game this doesn't play out so much as the game isn't so much a big dogfight as it's about deciding when to switch from passive to active sonar and launching guided torpedoes at the enemy from a range that's too close for them to evade from.
* ''VideoGame/SteelDiver'' is a submarine action/simulation hybrid that bends a few rules of reality, and has some submarines as enemies.
* In ''VideoGame/AdvanceWars'', sub-sub fights are quite common because submerged subs can only be attacked by cruisers and other subs. Given that cruisers are not constantly invisible and very vulnerable to battleships and bombers, they tend to be prime targets of opportunity and generally die quicker than subs. A sub attacking another sub will do between 55-65% damage; most sub battles end up with 8 HP on the attacker and 4 on the defender.
** Taken [[UpToEleven Up to Eleven]] with the fan [[SpriteComic Sprite Comic]] Bob Squad. At one point, a sub tries to attack a lander carrying the main characters. On their turn, the lander-[[CaptainObvious which can neither dive or attack]]-proceeds to do BOTH. [[HilarityEnsues Hilarity Ensues]].
* Because subs in most versions of ''VideoGame/{{Civilization}} are invisible except to each other and certain air units, they tend to be most useful for keeping one another at bay.
* ''VideoGame/FromTheDepths'': One of the best ways to deal with enemy subs is to send your own sub after them.
* ''VideoGame/SunlessSea'': The "Zubmariner" DLC, naturally, comes with many enemy submersibles to match your own against.
* Averted in ''VideoGame/PacificFleet'', where only the US Navy has submarines (ignoring RealLife Japanese subs), but possibly played straight in ''Atlantic Fleet'', where both the Brits and the Germans have them. The Germans actually have three sub classes, one of which is a more modern attack sub with faster submerged movement (still slower than most surface ships, though), no deck gun, and rapidly reloading torpedoes (1 turn vs. 3 for others). It's easy enough to set up sub-on-sub single matches, but the dynamic campaign doesn't allow subs to engage one another. Even if one side's fleet might have subs in it in the engagement area, the subs will not participate in said battle. As a rule, Germany will tend to spam subs in the campaign, in order to sink Allied shipping, while the Brits will spam destroyers in order to escort convoys and counter said subs.
* As it's set during the Cold War and is the spiritual successor to ''VideoGame/RedStormRising'', ''VideoGame/ColdWaters'' features ''lots'' of submarine combat, in addition to plenty of anti-surface attacks.

* ''Webcomic/{{Archipelago}}'' has a few submarine battles, although most are implied, with only one actually seen in the story so far. It was, however, epic, and involved grappling onto and then ''boarding'' the other sub. Without surfacing.
** Justified, as this section of the [[ConstructedWorld world]] consists entirely of scattered islands, and submarine is the routine method of travel. Warfare between submarines would be more common.

* [[Recap/TheSimpsonsS9E19SimpsonTide "Simpson Tide"]], an episode of ''WesternAnimation/TheSimpsons'' where Homer joins the Naval Reserve and is assigned to a nuclear submarine during a war games exercise. Predictably enough, [[HilarityEnsues he ends up in command after shooting the captain out of a torpedo tube (hitting an enemy sub) and nearly starts World War III.]]
** It was his first day!