How to back up your Subnautica 2 multiplayer save (and what to do if the host's PC dies)

Subnautica 2's multiplayer at Early Access launch is peer-to-peer, which means the world save lives on the host's machine and nowhere else. That's fine when everything works. It's a disaster the first time the host's drive dies, their Windows install corrupts, or they reinstall the game without thinking. I've seen the same pattern in Valheim and Grounded support tickets for years – the host loses the save, nobody else has a copy, and 40 hours of co-op base-building is just gone.

The whole point of this article is to make sure that doesn't happen to your group. The fix takes about two minutes and you should do it tonight.

TL;DR

Find your save folder, copy it somewhere that isn't your gaming PC, do that on a schedule. Folder location and the actual steps are below.

Where the save actually lives

Subnautica 2 stores its multiplayer save on whichever machine is hosting. If that's you, the file is local. If your friend is hosting, you don't have a copy at all – which is the whole problem.

I'm being deliberately careful with the exact path here because the game just released and a few guides are already quoting paths they haven't checked. The reliable way to find it on Windows is to open File Explorer, paste this into the address bar, and hit Enter:

%userprofile%\AppData\LocalLow\Unknown Worlds

That's where the original Subnautica kept its saves, and the sequel uses the same publisher's storage convention. Inside that folder you'll see a Subnautica 2 (or similar) directory containing per-slot save folders, usually named something like Slot0000, Slot0001.

If nothing's there, search your C: drive for a folder containing files named gameinfo.json or player.bin – that's the save signature.

On Xbox or Microsoft Store installs the path is buried under WindowsApps, which Windows locks down hard. Manual backup isn't really viable there – Xbox cloud saves are the only practical option, and they're enabled by default.

Backing it up by hand

Once you've found the folder, the actual backup is trivial:

• Close Subnautica 2 first. Copying a save while the game has it open can give you a half-written file that won't load.
• Copy the entire Slot0000 (or whichever slot your world is in) folder somewhere off your game's install drive. A second drive, an external SSD, Dropbox, OneDrive, Google Drive – anywhere that isn't the same physical disk as the original. The whole point is "if my PC dies, my save survives".
• Name the copy something useful. subnautica2-coop-2026-05-15 is a lot more helpful than Slot0000 - Copy six weeks from now when you're trying to figure out which backup is which.
• Repeat once a week if you play casually, or after every long session if you're deep into a base build.

If your group has someone comfortable with scripting, a Windows Task Scheduler entry that zips and copies the folder once a day is even better. It runs in the background, you forget it exists, and one day it saves your run.

Restoring on a new host

If the original host's PC has gone to the great recycle bin in the sky and you're starting over on someone else's machine, the restore is the reverse:

1. Install Subnautica 2 on the new host's PC and run it once. That creates the empty Subnautica 2 folder in the right place.
2. Close the game.
3. Copy your most recent backup into %userprofile%\AppData\LocalLow\Unknown Worlds\Subnautica 2\, keeping the Slot0000 naming.
4. Launch the game and the save should appear in the load list.

The one thing that doesn't transfer cleanly is the host's ownership – the new host is the new host, full stop. Everyone else in your group joins the new session the same way they joined the old one (Friends List or friend codes, covered in the crossplay invite troubleshooting article).

A bigger fix that needs Unknown Worlds to land first

I want to be honest about the limits. As long as Subnautica 2's multiplayer is peer-to-peer, the host's PC is a single point of failure no matter how diligently anyone backs anything up. The real fix is dedicated servers, which haven't been announced. Until they land, manual backups are the best you can do, and they're genuinely effective – they're just on you to remember.

We're tracking the Early Access roadmap closely; if Unknown Worlds ship a dedicated server tool, we'll have a server product live within days and an updated guide alongside it. For now, copy the folder, store it somewhere safe, do it again next week.