The Oberon class was one of the most advance types of conventional submarines in any navy, combining high speed with great underwater endurance. They were attack submarines, with both anti-surface and anti-submarine capabilities. Designed specifically for silent running, they were amongst the quietest operational submarines in the world, including nuclear submarines. They were therefore extremely difficult to detect and were ideally suited to operations on an enemy’s “doorstep”. Equipment included sensitive long-range underwater listening devices and electronic fire-control systems. They were fitted with a “snort” system, which enable batteries to be recharged while the submarine remained submerged. Moulded fibreglass had been used extensively in the construction of the casing and fin (sometimes referred to as the 'sail').