... vents & geysers, wrecks, Degasi seabases and general resource locations. Subnautica - Subnautica is an underwater adventure game set on an alien ocean planet. A massive, open world full of wonder and peril awaits you!Dive Into a Vast Underwater WorldYou have crash-landed on an alien ocean world, and the only way to go is down. Subnautica - Subnautica is an underwater adventure game set on an alien ocean planet.