Subnautica 2 Guide: How Multiplayer and Co-Op Works
Alterra finally figured out how to send backup, but surviving together comes with its own set of rules.
The original game thrived on crushing isolation, but Subnautica 2 allows you to bring up to three friends along for the ride. The game is fully playable solo, and there are absolutely no multiplayer-exclusive areas or forced co-op mechanics. However, if you want to build a massive base together or simply have someone to scream with when a leviathan attacks, you need to understand how the servers actually function.
Hosting and Joining Games
Setting up a session is incredibly straightforward, but the game gives you a few different options depending on whether you want a fresh start or to carry over your existing progress.
Converting Your Single-Player Save
If you already spent ten hours building a base by yourself, you do not have to start over. Go to the main menu, click "Play Single Player," select your save file, and choose "Convert to Multiplayer." You can then host the game and invite your friends. If your friends log off and you want to continue alone, simply hit "Host Multiplayer," select the save, and choose "Convert to Single Player."
Inviting Friends and Crossplay
Subnautica 2 fully supports crossplay between PC and Xbox. If you are already platform friends, you can just open the pause menu, select your Friends List, and hit invite.
If you are playing with someone on a different platform, you need to use the "Join Friends" menu on the title screen. This generates a friend code you can share to add them to your in-game list. Once they are on the list, you just invite them to your session like normal.
How Progression and Inventories Work
The way the game handles your shared progress is a bit of a mixed bag. It is incredibly generous with world progression, but character progression is strictly isolated.
Shared Blueprints and Missions
The best part of co-op is the shared database. If you scan a fragment for a new blueprint, everyone in the session instantly gets access to it. The same goes for databank entries and black box missions. You only need to find one black box to advance the story for the entire group. Anyone in the session can toggle waypoints for bases, structures, or Scanner Station pings, meaning you can easily coordinate your exploration without getting lost.
The Fresh Character Catch
Here is the friction point. If you invite a friend into your established world, they do not inherit your character progression. They drop in as a brand-new character with a completely empty inventory.
They will not have any of your DNA Adaptations or personal upgrades. They have to scan their own Angel Combs to cure their Digestive Incompatibility, which I covered in my Subnautica 2 Food and Water guide. You can give them spare tools to get them started, but they still have to grind out their own genetic upgrades.
Base Building and Exploration
Once everyone is geared up, the multiplayer restrictions loosen up completely.
Total Base Freedom
Base building is entirely collaborative. There are no permission locks. Anyone in your session can build new rooms, deconstruct walls, and access any storage locker. This is fantastic for a coordinated group, but be warned: anyone you invite has the power to completely dismantle your base or drain your resources.
No Tethering or Revives
You are not chained to your co-op partners. I tested this, and players can explore hundreds of meters apart without hitting any artificial barriers or tethering systems. You can have one person farming quartz in the shallows while another explores the deep ruins.
Just be aware that if you die out there, your friends cannot help you. There is no revive mechanic. If your oxygen runs out or a predator gets you, you immediately reprint back at the nearest Biobed and drop some of your inventory, exactly like single-player. Your friends can grab your dropped items to save you a trip, but that is the extent of their help.
