The first design of a missile that could be launched from a submarine was developed by the Germans near the end of World War II.
It involved a launch tube which contained the missile and it was basically towed behind the submarine. These early systems meant that the submarine had to surface in order to fire the missiles.
During the 1950s and 1960s launch systems were adopted to allow the missiles to be successfully launched under water without the submarine having to surface and become vulnerable to enemy attacks. Being able to launch missiles under water makes submarines invisible to reconnaissance satellites.
The missiles are launched from underwater in a vertical missile tube inside the submarine. After they have been launched they ascend to the surface at a very high speed inside a nitrogen gas bubble that prevents them from getting wet.
Only after they had surfaced, internal gyros let the missile know when it starts to fall back towards the water and this triggers the rockets to fire, sending the missile towards its intended target.
