Multiplayer and co-op

Subnautica 2 supports 1-4 player online co-op, making it the first mainline Subnautica game with official multiplayer support. (The original Subnautica had a popular community mod called Nitrox that added multiplayer.) The system was detailed in Dev Vlog #5 ("Diving Together in Multiplayer"), released February 10, 2026.

Design philosophy

Design Lead Anthony Gallegos has been explicit about the boundaries: "The important distinction there is that any part of the game isn't going to require cooperative play." No puzzles need two players, no areas are locked behind multiplayer, and the full game can be completed solo from start to finish.

This was a direct response to community concerns that adding multiplayer would water down the isolation and tension that defined the original. The Subnautica series built its reputation on the dread of diving alone into dark caves full of predatory leviathans. Unknown Worlds designed co-op as an optional addition rather than a fundamental restructuring.

Session management

The system uses drop-in/drop-out design. Players can start a game in multiplayer from the beginning or convert an existing solo save into a co-op session at any time. Friends can be invited through their platform's friends list (Steam, Xbox) or through Subnautica 2's own cross-platform friends list.

There is no local split-screen support. Voice chat at launch relies on Discord or platform options. The developers are exploring proximity voice chat but haven't confirmed it for Early Access.

Cross-play

Cross-play between PC and Xbox is confirmed. The game is also compatible with handheld devices including Steam Deck and the ROG Ally series.

Camera and animation

Players in co-op can independently choose between first-person and third-person camera views. Dev Vlog #5 revealed that adding co-op required the animation team to create visible player movement animations for the first time, since the previous games were single-player only and never needed to render the player character's body for others to see.

Shared bases and resources

When playing together, players share bases. Power management becomes a collective responsibility since life support systems need to stay active for all four divers. Running out of power affects everyone. This creates natural coordination incentives around resource gathering and base expansion.

Network architecture

Leaked milestone documents revealed that the multiplayer architecture shifted from dedicated servers (the original plan) to peer-to-peer networking. This change was part of the scaled-back Early Access scope. The Dev Vlog #5 team included backend engineers Sverrir Berg and Jon Bjarnason, along with Lead Gameplay Engineer Adrian Lopez-Mobilia and programmer Sam Dark.

Community context

Co-op has been one of the most requested features since the first Subnautica launched in 2018. The Nitrox mod supporting up to 100 players demonstrated the demand, building a community of approximately 70,000 Discord members. At the same time, many fans feared multiplayer would change the core identity. Unknown Worlds' approach of making co-op entirely optional aims to satisfy both camps.