Should the sea dragon breathe fire? Does the reaper really need mandibles? Could a ghost leviathan get as big as it is? In this video, I analyze Subnautica from a scientific standpoint to determine just how realistic it is. We take a look at the planet itself, the environments, and the plethora of life inhabiting 4546B to examine how authentic and believable the world of Subnautica is to a marine biologist.