Early transhumanism, born of biotechnological discoveries, greatly improved the variety of human beings. Deepguard is a general term for military units consisted of individuals whose bodies were modified to remain submerged for indefinite time, not fearing decompression sickness, able to withstand significant pressure, and often doing well with no means of atmospheric breathing whatsoever. These units treat vast ocean depths much like traditional infantry does unexplored lands: a source of danger, opportunity, and perhaps future home.