A torpedo tube is a device for launching torpedoes in a horizontal direction.

There are two main types of torpedo tube:

• Those designed to operate below water level, as fitted to submarines.
• Deck-mounted torpedo launchers as used on surface ships.

Some authorities prefer to reserve the term torpedo tube for submarine type torpedo tubes, referring to deck-mounted units as torpedo launchers, but the more general use has long been widespread among both lay people and arms manufacturers.

There are essential differences between the two types other than the obvious one of operating in air as opposed to water. Deck-mounted launchers are normally designed for a specific munition, and often for a particular model of that munition. On the other hand, the torpedo tube is the submarine's general purpose launcher, and the only one capable of being reloaded while submerged. Missile tubes and the newer vertical launchers by way of contrast are each loaded with a single round while in port.

The more recent designs of submarine torpedo tube may even be used for more than one size of torpedo, as well as other munitions including mines and cruise missiles. Submarine tubes of greater than 21 inches in diameter are designed to accept the standard 21 inch heavy torpedo as well as larger munitions.

Some nuclear submarines, both US and Soviet, were fitted with two sizes of torpedo tube. On these boats a set of smaller tubes were dedicated to firing torpedoes, while the larger tubes were intended to fire a wide variety of munitions. This provided versatility and firepower while saving space, cost and complexity over an armament of all larger tubes.

On the older Soviet boats such as the Hotel class submarine, the smaller tubes were 16 inch, with the general purpose tubes being the standard 21 inch. On others, such as the Soviet Akula class submarine, the smaller tubes were 21 inch. More recently both navies appear to be returning to a smaller number of only 21 inch tubes.

See torpedo for a list of torpedo sizes.