Subnautica is a 2018 action-adventure survival game created and published by Unknown Worlds Entertainment. The player controls Ryley Robinson, a character who survives a spaceship crash on an alien ocean planet and explores it freely. The main goals are to gather important resources, avoid dangerous plants and animals, and find a way to leave the planet.

The game was first available for purchase before it was finished on Windows in December 2014, macOS in June 2015, and Xbox One in May 2016. It was fully released for macOS and Windows in January 2018, with versions for PlayStation 4 and Xbox One in December 2018. The physical copies for consoles were published by Gearbox Publishing. Versions for Nintendo Switch, PlayStation 5, and Xbox Series X/S were released in May 2021. A version for Nintendo Switch 2 was released in February 2026. Critics gave the game mostly positive reviews, and it sold over 5 million copies by January 2020.

A related game, Subnautica: Below Zero, which was originally planned as extra content for the main game, was released in May 2021. A new game in the same series, Subnautica 2, is expected to be available for purchase before it is finished sometime in 2026.

Gameplay

Subnautica is a survival game that combines action and adventure, set in a large, open world and played from a first-person perspective. The player controls Ryley Robinson, the only survivor of a crashed spacecraft called The Aurora, who is stranded on a faraway ocean planet named 4546B.

The main goal is to explore the ocean, survive its dangers, and complete tasks to move the story forward. Players can gather resources and blueprints, build tools, construct bases and submersibles, and interact with the planet’s wildlife. Some of the most dangerous creatures include Crabsquids, Warpers, Mesmers, Bonesharks, Ampeels, Stalkers, Crashfish, and large creatures like the Reaper, Sea Dragon, and Ghost Leviathans.

Most of the game takes place underwater, with two islands to explore. The game includes a day-and-night cycle that changes visibility, and eclipses occur often. When starting a new game, players can choose from four difficulty modes:

• In Survival Mode, players must manage their health, hunger, thirst, and oxygen levels. If they die, they restart but lose some items from their inventory.
• In Freedom Mode, gameplay is similar to Survival Mode but without hunger and thirst.
• In Hardcore Mode, players face permanent death. If they die, they cannot restart, and their save file is deleted. They also do not receive warnings about low oxygen levels.
• In Creative Mode, all depleting stats like health and thirst are removed. All blueprints are unlocked, allowing players to craft items without needing resources. Players start with a stasis rifle, Seaglide, mobile vehicle bay, and propulsion cannon. Items, bases, and vehicles do not require energy to operate, and vehicles are immune to crush depth.

The game works with VR headsets like the HTC Vive and Oculus Rift. Players can use a keyboard, mouse, or game controller for input.

Plot

About 1,000 years before the game begins, an alien group called "the Architects" studies the ocean planet 4546B to find a cure for Kharaa, a disease that has severely harmed their people. They learn that the Sea Emperor Leviathan naturally creates a cure, called "Enzyme 42," in its digestive system. However, the last remaining Sea Emperor is too old to make enough of the enzyme, and efforts to hatch its eggs to collect the enzyme fail. As the situation worsens and Kharaa accidentally spreads throughout the ocean, the Architects place 4546B under automatic isolation and leave the planet.

Centuries later, the spaceship Degasi crashes on 4546B while searching for minerals. Three of its crew survive for some time on the planet, but they are no longer alive or present when the game begins. Ten years later, the spaceship Aurora from Alterra Corporation crashes on 4546B while searching for the Degasi wreck. The player character, Ryley Robinson, is one of many Aurora crew members who escape in pods. He is knocked unconscious during entry into the planet's atmosphere and is the only survivor when he wakes up. Ryley is contacted by the trading ship Sunbeam, which responds to the Aurora's distress signal. When Sunbeam tries to rescue Ryley, it is destroyed by a large alien weapon.

Ryley investigates and finds the weapon is the Architects' "Quarantine Enforcement Platform," which automatically attacks any ship trying to enter or leave the planet to stop Kharaa from spreading. Ryley tries to disable the weapon, but the control panel sees he is infected with Kharaa and ignores his commands.

Ryley explores the planet and learns about the Architects through their facilities. He eventually finds the last living Sea Emperor, which is held in an Architect containment area and can communicate mentally. Ryley activates a teleporter inside the Sea Emperor's aquarium to allow its young to escape. In return, the Sea Emperor gives Ryley the recipe for an enzyme that helps its eggs hatch. Ryley uses the enzyme to hatch the eggs, and the young Sea Emperors release large amounts of strong Enzyme 42 into the environment, curing Ryley and all other infected organisms on 4546B. The Sea Emperor then says goodbye and dies peacefully.

Now cured, Ryley can disable the Quarantine Enforcement Platform, build an escape rocket using blueprints from the Aurora wreck, and leave the planet. In its final mental message as Ryley departs, the Sea Emperor compares itself to Ryley. The game ends here.

In a post-credits scene, Ryley's PDA informs him he cannot land until he pays 1 trillion credits to Alterra for using their resources. The natural resources of 4546B are considered the private property of Alterra.

Development

Subnautica was announced by Unknown Worlds Entertainment on December 17, 2013. Charlie Cleveland was the director and lead gameplay programmer, and Hugh Jeremy was the producer. The music was composed by Simon Chylinski.

Charlie Cleveland was inspired by Minecraft, which he said "changed the game industry" and "moved away from traditional challenge and progression-focused games." The release of Minecraft happened at the same time as Natural Selection 2, a game made by Unknown Worlds. After feeling tired from working on Natural Selection 2, the team wanted to try something new and decided to create a game like Subnautica. Other influences included scuba diving, the films of James Cameron, and the feeling of exploring the deep, dark, and sometimes beautiful or dangerous parts of the ocean. Cleveland did not originally think of the game as a survival game but as an exploration game. The team also wanted to make a non-violent game without guns after the Sandy Hook school shooting.

The development team chose to use the Unity engine instead of Spark, the engine used for Natural Selection 2. Hugh Jeremy, the producer, explained that Unity better meets the game’s needs. He said, "Because our team does not include people who work on Spark, it is not appropriate for Subnautica to use Spark. Using Unity allows Spark to develop in one direction while Subnautica develops in another. Using Spark for Subnautica would not be a good fit."

Subnautica does not have a traditional mission or quest structure. This was a deliberate choice. Cleveland said, "With intrinsic rewards, players are encouraged to do activities for their own enjoyment. If they get past the learning period, they will find the activities pleasurable on their own." Cleveland made this choice after reading an essay by Jamie Cheng, who used similar ideas in his game Don't Starve.

Early access versions of Subnautica were released on Steam Early Access on December 16, 2014, and on Xbox One Preview on May 17, 2016. At first, the game did not include hunger or thirst mechanics. After receiving feedback, especially from one player whose comment "struck home," the team added these systems. They found that it helped players understand the early parts of the game. The full version was released on January 23, 2018, for macOS and Windows, and on December 4, 2018, for PlayStation 4 and Xbox One. The Nintendo Switch, PlayStation 5, and Xbox Series X/S versions, along with a spin-off called Subnautica: Below Zero, were released on May 14, 2021. Below Zero was released in early access on January 30, 2019.

In May 2025, game publisher Pladigious announced that Subnautica would be released on Android and iOS on July 8, 2025. As of that date, the game is available for download on both platforms. The mobile version includes the complete original game with all core modes—Survival, Freedom, and Creative—optimized for mobile play. It also has cloud saves, controller support, and a redesigned interface for touchscreen controls.

Reception

Before Subnautica was released, it received positive feedback from critics. Ian Birnbaum of PC Gamer compared Subnautica to "an underwater Minecraft," noting that "with a skilled developer leading the project and many different underwater environments to explore, it will be difficult for Subnautica to fail. As players gain more tools and learn about the game's final challenges, Subnautica will show how survival games can be exciting, challenging, and enjoyable." Marsh Davies of Rock, Paper, Shotgun praised the game's rewarding exploration but pointed out that some in-game recipes were not easy to understand.

At its release, Subnautica received "generally positive reviews" on all platforms, according to Metacritic.

By January 2020, over 5.23 million copies of the game had been sold on all platforms.