Subnautica 2: How to Convert Your Solo Save to Co-Op (And What You'll Lose When You Do)

So your friend just bought Subnautica 2 and wants in on your world. Great news: you can absolutely let them in. Less great news, they're showing up with nothing. No gear, no DNA upgrades, no blueprints. Just vibes and a prayer.

Before you hit that convert button, here's exactly what happens when you flip a solo save to multiplayer, what carries over, what doesn't, and what you need to do to get your squad actually playable before you both go charging into the deep end.

Multiplayer Quick Guide

How to Actually Convert the Save

It's a two-step job, and it takes about thirty seconds.

1. Boot the game and go to the main menu.
2. Hit Play Single Player.
3. Select the save you want to convert.
4. Choose Convert to Multiplayer.
5. Host the session and send your friend an invite.

That's it. Your existing world, your base, your gear, your progress, all of it stays exactly as you left it. Nothing gets reset on the host's end.

And if your squad logs off and you want to keep playing solo? Same process in reverse. Hit Host Multiplayer, select the save, and choose Convert to Single Player. You can bounce between solo and co-op as many times as you like without any penalty.

What the Host Keeps

Everything. Genuinely, nothing changes for you as the host.

• Your base stays intact, every room, every module, every item in storage.
• Your full personal inventory carries over.
• All your DNA Adaptations and biological upgrades remain active.
• Every blueprint and scan you've already unlocked stays unlocked.
• Your story progress and biome exploration state don't reset.

If you've spent ten hours building a solid base in the Sparse Plains, those ten hours of work are still there when your friends join.

What Guests Get

When a friend joins your converted world, they do not inherit your progress. They drop in as a brand new Pioneer with:

• An empty inventory.
• No DNA Adaptations whatsoever.
• No personal blueprints beyond the starting ones.
• Zero crafted gear.

Think of it less like "my friend is joining my save" and more like "my friend just crash-landed on the same planet I'm already set up on." They're starting from scratch in a world that already has your established base in it, which is actually fine, because at least they've got somewhere to sleep.

The one thing that does carry across to guests? Scans and blueprints that are registered to the base's shared systems rather than to you personally. So if you've unlocked something in the world that gets logged universally, they'll benefit from that. Personal character progression, though? Fully separate.

The DNA Adaptation Issue

The immediate issue is Digestive Incompatibility. In Subnautica 2, your Pioneer starts out unable to properly process the alien food and water sources on Zezura. You fix this by interacting with an Angel Comb organism, which gives you the Digestion Adaptation and lets you actually survive off the local ecosystem. Your guest doesn't have this yet.

Before you go anywhere exciting together, your first priority should be getting your friend to their Angel Comb. They can't really function without it, and you don't want to be babysitting their food and water situation while you're trying not to get eaten by a Leviathan.

The good news: Angel Combs stay permanently active after the first interaction. So once your guest touches theirs, it's done.

Getting a New Guest Up to Speed: A Checklist

If you want your friend to be functional within the first hour rather than flailing around for three, run through this before you do anything else together:

Immediate priorities:

• Point them at the nearest Angel Comb so they can sort their Digestion Adaptation.
• Hand them a spare O2 Tank from your storage if you've got one.
• Give them a Scanner so they can start filling their own codex.
• Craft them a Biosampler if your base has the materrials, because their DNA progression is completely separate to yours.

Before any deep dives:

• Make sure they've scanned the local Sparse Plains creatures for their own modification pool.
• Check they've got a Tadpole or access to one, swimming everywhere without a vehicle is miserable.
• Brief them on the Collector Leviathan because they will not expect it, and it will ruin their day.

Base housekeeping:

• Designate one storage locker as shared materials, so nobody accidentally spends your rare minerals on starter gear.
• Show them where the Biobed is, so they know where they respawn on death.