A submarine is a warship that performs its mission beneath the seas. When equipped with modern weapons and systems a submarine can attack targets under or on the water, on the shoreline or far inland or, instead, loiter near a coastline to gather valuable intelligence.

Because a submarine operates stealthily, hidden within the ocean, it is a powerful threat to an opponent’s Navy and, when equipped with appropriate missiles, to its land-based facilities.

Because submarines operate covertly, their presence is a distraction to an opponent’s attempts to implement its plans, necessitating the diversion of forces that could be used elsewhere.

For these reasons, submarines are a core defence requirement for maritime nations.

Submarines are among the most complex of military machines with, typically, over 70 systems incorporated in a conventionally powered submarine.


Submarines work in the demanding environment of the deep oceans and must be designed not only to withstand enormous water pressure but to recover in the event of an accident. The environment below the waves is complex and submarines must be able to manoeuvre effectively and stealthily in a variety of circumstances.

Everything demanded of a submarine must be accommodated within the confined space of a pressure hull. The dimensions of this are itself dictated by what the operating Navy wants the submarine to do.

Weapons, systems, propulsion, fuel, food, water, air and, above all, provision for crew to operate effectively and safely all compete for space. As well as accommodating these demands, the hull must also provide the desired range, speed, manoeuvrability, resilience and safety.

Balancing the requirements of these factors determines the nature of a submarine’s design. The constraint of the volume of the pressure hull makes it difficult to significantly change the balance of the factors in a submarine’s design without having to start a new design process.

For this reason, success in the acquisition of a new class of submarine depends on an early and clear decision on the roles and capabilities required of the submarine during the early stages of the concept design of the project.

More information on the essentials of submarine development and design can be found in Section 1 of the Future Submarine Industry Skills Plan (PDF).