Hot Sub-On-Sub Action

In the long history of submarines being used in warfare, which goes back at least to 1775... how many times do you think a submerged submarine has sunk another submerged submarine? 500? 200? 100? 50? 10?

Actually, just once, during Operation Caesar in World War II, when HMS Venturer sank U-864. Good thing for the Allies too, since the U-864 was transporting advanced technology to Japan.

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 - the 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, all of them small RO-class boats, were credited to the USS Batfish during a single three-day period in February 1945. Two U-boat kills were also credited to American submarines, one being during WWI. Neither was confirmed.

However, whilst the crew of the HMS Venturer only had paper, pencils and decent maths skills to plot a firing solution, modern subs have computers and advanced homing torpedoes - had the Cold War 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, Tom Clancy!). 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 nuclear attack submarines (SSN) which include enemy sub-killing in their tasking - these are generally known as "Hunter-Killer" submarines.

Anime and Manga

 * Submarine 707 R (Mission 2)
 * The Silent Service
 * 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.
 * Blue Sub 6

Film

 * The Hunt for Red October is the Trope Codifier.
 * Crimson Tide
 * U-571 does this, with the Americans in the captured German U-Boat destroying another submerged German U-Boat with torpedoes.
 * G.I. Joe: The Rise of Cobra features what amounts to a dogfight UNDER WATER!
 * It also features what amounts to the trench run in Star Wars Episode 4 UNDER WATER!.
 * Down Periscope involves a wargame that tests if a rogue World War Two-era diesel submarine, run by a Ragtag Bunch of Misfits, 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 (Kelsey Grammer), in place of the flares.
 * The Abyss deserves a mention here. The minisubs involved aren't fighting with weapons- they're fighting over a weapon.
 * And fighting without weapons means ramming each other, brutally. Brilliant, and vastly under-rated action sequence.
 * Another particularly brutal minisub duel occurs in the James Bond film For Your Eyes Only. 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 Roger Moore's stunt double.
 * Run Silent Run Deep depends on, and arguably laid the groundwork for this trope.
 * It is torpedoed when it is lured to the surface rather then 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 World War II.

Literature

 * The Hunt for Red October
 * See also Red Storm Rising, and a rather one-sided version in The Sum of All Fears.
 * Averted in Das Boot and The Enemy Below. Both of these are German U-boats versus Allied surface ships. In Das Boot, the only encounter the U-Boat has with another submarine is almost colliding with one when they are both on the surface.
 * And one of their own subs at that.
 * Most WWII sub movies are sub vs surface. Hot Sub-On-Sub Action is associated with postwar era. At least there Hollywood Tactics are correct.
 * Though a Japanese sub is sunk in Run Silent, Run Deep. They had to lure it to the surface, and then fire the torpedo under a ship to hit the enemy sub.
 * There's a sub v. sub fight in, of all places, Zombie Apocalypse novel World War Z. And no, neither sub was piloted by Zombies. If they were, this entry would be on the Crowning Moment of Awesome page.
 * To expand, 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..
 * The Dragon In The Sea (AKA Under Pressure) by Frank Herbert depicts tense underwater combat Twenty Minutes Into the Future between nuclear submarines. Despite being published in 1956 it has survived the ravages of Science Marches On and Zeerust remarkable well.

Live Action TV

 * SeaQuest DSV, in its third season had actual sub fighters - the Specter-class for the UEO forces, and a host of other types for various bad guys forces.
 * The Japanese 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 Japanese female pilot. Yes, they kill off one Twofer Token Minority (a black woman) to immediately replace her with another.

Video Games

 * In the Hunt 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 Living Statue.
 * Final Fantasy VII has a minigame where you pilot a submarine to seek and destroy another submarine.
 * Red Faction 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.
 * Submarine Titans, a real-time strategy game taking place underwater with subs. Combat occurs at close range, but stray torpedoes can hit targets at a distance.
 * Sid Meier also did a game version of Red Storm Rising, which, like the novel mentioned above, has plenty of this.
 * Completely averted in the sequel, though. Japanese subs didn't even have any sprites.
 * Also averted in the NES version - there were no other subs. The %@&! kaiboken, on the other hand...
 * Dangerous Waters.
 * The 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.
 * PS 1 game Critical Depth was basically Twisted Metal UNDERWATER. Subs ranged from a wooden pirate sub with cannons to a converted private jet. It was not very realistic.
 * X-COM: Terror From The Deep 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).
 * Supreme Commander features submarines as an entry level navel 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 to expensive to produce in large numbers.
 * The Forged Alliance expansion pack adds torpedo bombers for each of the factions as a counter to this. Like the destroyer, they cannot be mass-produced in the numbers that submarines can, but it can destroy enemy subs without risking being hit by return fire (from the subs).
 * Warship Gunner 2 allows you to engage enemy subs underwater if you're controlling a submarine. Note that you are completely Point Defenseless while submerged and submarines usually attack with torpedoes.
 * Pretty much averted in Warcraft 2. Submarines and sea turtles must surface to fire and can only be fired upon if a flying unit (griffon, dragon, helicopter, or zeppelin) can see them.
 * In Command & Conquer: 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 dolphins.
 * Steel Diver is a submarine action/simulation hybrid that bends a few rules of reality, and has some submarines as enemies.
 * In Advance Wars, 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.

Web Comics

 * 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 world consists entirely of scattered islands, and submarine is the routine method of travel. Warfare between submarines would be more common.

Western Animation

 * An episode of The Simpsons