Subnautica 2 Co-op & Multiplayer Setup

Subnautica 2 co-op is the series' first native multiplayer system — not a mod, not a workaround, but built into the game from the ground up. Co-op & multiplayer mode is explained on this page: how the system works, which limitations apply and how to set up a session properly.

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Co-op & Multiplayer in Subnautica 2 — The Basics

According to lead engineer Jon Bjarnason of Unknown Worlds, Subnautica 2 was designed with multiplayer support from the very beginning of development. Even so, the game is primarily built as a single-player experience — the co-op mode is entirely optional. No piece of content, no puzzle and no story sequence requires more than one player.

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Host System and Save File

The co-op model is based on a host-guest principle: the host loads a save file, and that save becomes the shared game world. Guests connect using an invite code and can join or leave the session at any time without putting progress at risk.

:::warning Important: the save file belongs to the host The save file belongs exclusively to the host. If the host is offline, guests cannot load the shared world. In the Early Access build there is no host migration — if the host drops out, the session ends for everyone taking part. :::

• The host can convert an existing single-player save into a multiplayer save — and back again — without losing progress.
• Starting a new multiplayer save is also possible.
• Guests can join even when the host world is already far advanced. Missed story sections are not caught up automatically.
• When a player dies, some carried items are dropped. Other players can pick them up. Manually reviving a teammate is not possible.

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Setting Up a Session — Step by Step

As the Host

1. In the main menu, choose "Host Multiplayer" → "Host New Multiplayer Game".
2. Select the game mode and save file, then confirm with "Host Game".
3. In game: open the pause menu → "Friends List" → invite friends via invite code or friends list.

Joining as a Guest

1. In the main menu, select "Join Friends".
2. Join via the cross-platform friends list or enter the host's Friend Code.
3. Confirm the invitation pop-up → spawn in the host's save file.

Converting a Single-Player Save

1. In the main menu, go to "Play Single Player" → highlight the save file you want.
2. Click "Convert to Multiplayer" — base, inventory and quest progress are kept in full.
3. Converting back to solo is possible at any time by the same route.

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Setting Up Crossplay

Crossplay works between PC (Steam, Epic Games Store, Windows Store / Xbox on PC) and Xbox Series X|S. The connection runs through Epic Online Services as a shared matchmaking layer — the platform-native friends lists (Steam, Xbox) are not linked to one another.

For cross-platform groups, this means:

1. In game: pause menu → "Friends List" → click "Generate Code".
2. Share the generated Friend Code (alphanumeric) via Discord, Steam chat or similar.
3. The recipient opens "Join Friends", enters the code and confirms — after that the player stays in the in-game friends list permanently.

:::warning Check the build version Hotfixes appear frequently during Early Access. If host and guest are on different build versions, the connection attempt fails silently. Ask everyone involved to update before a session. :::

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Shared Progress — What Gets Synchronized?

Note: At the Early Access launch there are no separate inventories for storage lockers. Unknown Worlds has announced that it will add this option over the course of Early Access.

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Game Modes and Limitations

• The entire game — all biomes, story content and craftables — is playable without co-op.
• There are no multiplayer-exclusive contents or mechanics.
• Splitscreen and LAN mode are not available.
• Every player needs their own license (purchase or Xbox Game Pass access).
• Players can spread out freely across the world, there is no tether system or distance limit.
• On death you respawn at the Lifepod — no team revive possible.

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Common Connection Problems