Project Force: Who will win the underwater arms race?

A look at how military forces around the world are reinventing the submarine for future conflicts.

New designs, new technologies and new weapons are shaping the submarines of the future, which are being manufactured right now, in response to global demand for more potent and flexible designs. Old Cold War fleets are being replaced and conventional subs – smaller but still useful – that can remain underwater for weeks are being built. Non-nuclear submarines use combustion engines that need oxygen to work. These are fine on the surface but, submerged, they must rely on battery power to operate. Depending on the battery type, submarines cannot submerge for long and need to resurface to recharge their batteries, putting them in a vulnerable position and open to detection by the enemy.