In the year 3020, humanity has come a long way but religious war continues. Years of technological innovation have left the oceans full of polluting liquids, which have settled into different layers. Since all land is required to house and feed the population, religious factions have turned to the oceans for their battleground.
Each submarine can adjust its buoyancy to settle beneath the surface of any liquid layer. In the same way, the buoyancy of torpedoes must be chosen to target the infidels. Torpedoes are automatically loaded and fired.