Originally designed for Cold War operations in the Mediterranean and North Atlantic the Trafalgar Class design was a follow on from the successful Swiftsure Class but incorporated many improvements making them both faster and quieter.

The hull of is covered by anechoic tiles to absorb sonar signals and noise reduction is achieved through the pump jet propulsion system which is a multi blade rotor turned by a jet of water that is quieter than a conventional propeller. The lead ship HMS Trafalgar was completed in 1983 before the pump jet propulsion system was ready and has a seven bladed propeller instead.

Like previous British nuclear submarines the Trafalgar Class boats have a ‘teardrop hull’, the fin has been strengthened and the hydroplanes can be retracted to allow the submarine to surface through ice.

The principle role of these "hunter-killer" vessels is to attack ships and other submarines and in this capacity they could support and protect a convoy or taskforce. With the fitting of the Tomahawk cruise missile system they will also be capable of a land attack role.

The Trafalgar Class are fitted with cameras and thermal imaging systems that allow them to be used in a surveillance role.