After surfacing , Jack finds himself the only survivor of the crash , and swims to a nearby lighthouse on an island , where he finds a bathysphere which he uses to sink into the ocean and enter the city of Rapture . After surfacing , Jack finds himself the only survivor of the crash , and swims to a nearby towering lighthouse on an island , where he finds a bathysphere which he uses to descend into the ocean and enter the city of Rapture .