Subnautica is a survival, adventure game set in an open world environment and played from a first-person perspective. The player controls the lone survivor of a crashed space ship, called the Aurora, on the fictional ocean planet 4546B. The ship's wreckage explodes shortly after starting the game, from which point onward it can be explored. The main objective of the player is to explore the game's world and survive the dangers of the planet while at the same time following the story of the game. Subnautica allows the player to collect resources, construct tools, bases, and submersibles, and interact with the planet's wildlife. In the basic difficulty "Survival", the player will have to maintain nutrition, hydration, and oxygen. The game includes a day and night cycle which affects the gameplay and surroundings. The game includes three other modes: "Freedom mode", in which hunger and thirst are disabled; "Hardcore mode", which is the same as Survival, except that if the player dies, the player will no longer be able to respawn; and "Creative Mode", in which the hunger, thirst, health, and oxygen features are all disabled, all the crafting blueprints are acquired, where no resources are needed to craft and the submersibles do not need energy and cannot be damaged. The game is mainly set underwater, with two explorable islands.