This is the British Royal Navy's newest class of submarine, the Astute. This nuclear-powered sub can generate its own air and water; sit in the English Channel and fire cruise missiles at North Africa; but perhaps the most extraordinary feature of the British-built sub is that it will never need to be refuelled throughout its 25-year lifespan, meaning it can sail round the world 40 times without surfacing. The cost: $2.33 Billion. The Brits have ordered three.