SMX-Ocean could replace other subs thanks to its efficiency and stealth French defence company DCNS Group has unveiled the SMX-Ocean Their concept for a new submarine aims to replace nuclear vessels They say this sub is just as big and even more capable It can stay submerged for three weeks and has 34 weapons on board Also uses a quieter form of propulsion that makes it less noisy There's no word yet on when such a submarine might enter service though Nuclear submarines are renowned for their enormous size and range of capabilities including operating for extended periods underwater. But now a company has unveiled a diesel electric submarine that can rival these bigger counterparts in size and ability. Called the SMX-Ocean, it is so advanced that it can stay submerged for three weeks and could cross the Atlantic six times without surfacing. French defence company DCNS Group has unveiled the SMX-Ocean (illustration shown). Their concept for a new submarine aims to replace nuclear vessels. They say this sub is just as big and even more capable. The advanced submarine was built by French naval defence company the DCNS Group. It is 330ft (100 metres long), 50.9ft (15.5 metres) high and 28.9ft (8.8 metres) across. On board it has a total of 34 weapons including torpedos, mines, anti-ship missiles, cruise missiles and anti-air missiles. This means it can attack targets across four areas: underwater, surface, land and air. Length: 330ft (100 metres) Height: 50.9ft (15.5 metres) Beam: 28.9ft (8.8 metres) Surface displacement: 4,750 tons Maximum diving depth: 1,150ft (350 metres) Maximum speed, submerged: 20 knots Range: 18,000 miles (29,000km) But it represents a breakthrough in submarine technology, as previously nothing had been able to compete with nuclear vessels. In order to be as capable as nuclear submarines it uses something known as Air Independent Propulsion (AIP). This technology allows a non-nuclear submarine to operate without needing access to atmospheric oxygen for long periods of time. This enables it to remain underwater They basically work by using a diesel engine operated conventionally on the surface but, underwater, they are supplied with an oxidant (such as liquid oxygen) that keeps them running. The SMX-Ocean also uses a quieter form of propulsion that makes it less noisy. There's no word yet on when such a submarine might enter service though. Its array of weapons means it could attack targets across four areas: underwater, surface, land and air (pictured is an animation of a missile hitting the ground) One of the benefits of using AIP over nuclear propulsion is that nuclear submarines must constantly pump coolant, which can be noisy. AIP submarines can be almost entirely silent and are therefore much more stealthy. According to Tyler Rogoway for Fox Trot Alpha, the SMX-Ocean is intended to eliminate the remaining advantages of nuclear submarines. It uses the latest AIP technologies in its larger hull design, namely the latest in fuel cell and lithium-ion batteries. This allows the boat to stay submerged for 21 days and remain out at sea for 90 days without coming in to port. This gives it the option of performing "blue water" (open ocean) operations as opposed to just "brown water" (on the coast). Amazingly the submarine even has unmanned underwater vehicles (UUVs) and unmanned air vehicles (UAVs) it can deploy and go out of its range of operation. 'The SMX-Ocean is most likely a vision of things to come in regards to subsurface warfare technology,' Mr Rogoway wrote. As nuclear submarine technology becomes increasingly unaffordable for even the most wealthy states, their capabilities will have to be shared by cheaper diesel-electric AIP boats.