Subnautica 2 Mods: How UE4SS Mods Work, Installing Them, and Co-op

Subnautica 2 mods exist, and plenty of people use them, but none of it is official. Unknown Worlds' support site says so directly: "At the start of Early Access, our focus is on the core experience, so official modding support will not be available initially." Everything available today is community-made, most of it runs through an Unreal Engine mod loader called UE4SS, and each game update can break it. By 28 September 2026 Nexus Mods listed 269 Subnautica 2 mods, and UE4SS itself had passed 165,000 downloads.

This page covers how Subnautica 2 mods actually load, how to install them, what the developer's own support team tells modded players to do after every patch, and how mods work in co-op, where there is no dedicated server to put them on.

Mods and Biomods are different things

Biomods are an in-game system: upgrades you unlock from Biolabs, with extra passive slots earned by scanning creatures. They aren't mods in the modding sense, and you don't install them. If you searched for "Subnautica 2 mods" hoping to unlock Biomods, that's gameplay. Creative mode, for example, "now unlocks all Biomods by default" since update 1.1.

How Subnautica 2 Mods Load

Subnautica 2 is an Unreal Engine 5 game. The UE4SS page for it gives the engine version as 5.6.1 and notes that the game is "largely written in native C++ code as opposed to managed C# in previous games". So modding tools built for the earlier, C#-based Subnautica games don't apply here.

Community mods come in two forms, and Unknown Worlds' own troubleshooting article names both locations:

Most gameplay mods are UE4SS mods: inventory size, storage, vehicle speed, cheat menus. UE4SS is effectively the prerequisite for modding Subnautica 2.

Installing UE4SS

Per the UE4SS for Subnautica 2 page on Nexus Mods:

1. Download the non-dev version of UE4SS for Subnautica 2.
2. Place the zip in the game's binaries folder. For Steam that is \Subnautica2\Subnautica2\Binaries\Win64, not the similarly named \Engine folder.
3. Extract it there, so dwmapi.dll and the ue4ss folder sit directly in Win64.
4. Install mods into \ue4ss\Mods. Each mod gets its own folder, usually with an enabled.txt inside.
5. Launch the game. A UE4SS.log file appearing in the ue4ss folder confirms it loaded.

Platform variations from the same page:

• Xbox Game Pass on PC: the folder is XboxGames\Subnautica 2\Content\Subnautica2\Binaries\WinGDK.
• Linux or Steam Deck (Proton): add WINEDLLOVERRIDES="dwmapi=n,b" %command% to the game's Steam launch options.

UE4SS does not work on the experimental branch

The UE4SS page states it is maintained for "the latest stable version of Subnautica 2" and that it "does NOT work on the experimental branch." If you've opted into Experimental, play unmodded.

Mods are a PC-only thing. The UE4SS install covers Steam and PC Game Pass. On an Xbox console there's no folder to put a mod in.

The Most-Downloaded Subnautica 2 Mods

Download counts from the Nexus Mods API on 28 September 2026. "Last updated" matters more than the download count: a mod that hasn't been updated since before 1.2 may not work on the current build.

The console and cheat mods have their own page: Subnautica 2 Console Commands and Cheats: Why the Console Needs a Mod.

After Every Game Update: Take the Mods Out

This is the part modded players most often get wrong, and Unknown Worlds repeats it in its patch notes. From the 1 September Buddy System hotfix: "If you play Subnautica 2 with mods, please temporarily disable, remove, or uninstall them before launching the game following the hotfix. Community mods will not be updated for compatibility with the latest hotfix, and may cause crashes or other unexpected behavior on launch."

Their support article for a game that crashes on startup after an update gives the exact steps:

1. Uninstall, disable or remove all installed mods.
2. If you use UE4SS, delete Subnautica2\Binaries\Win64\dwmapi.dll. That single file is what loads UE4SS, so removing it turns every UE4SS mod off at once.
3. Check Subnautica2\Content\Paks\~mods\ for leftover pak mods and remove them.
4. Launch again.

Then wait for each mod's author to publish an update before putting it back. Keep the dwmapi.dll and your Mods folder somewhere safe, and you can restore the whole setup in one go when your mods catch up.

Back up your saves before modding

Unknown Worlds recommends backing up saves "any time you switch between versions". Mods that change inventories, storage or unlocks write their changes into your save. The Cheat Toggles author says the same: "Making a backup of your save file is highly recommended before you install and use this mod!"

Mods in Co-op

Subnautica 2 co-op is peer-hosted. One player hosts from their own save, up to three friends join (four players in total), and the session exists only while the host is in the game. There's no separate server program and no server folder to install mods into. Every mod lives on a player's PC.

What that means in practice:

• Host-side mods exist. The Too Many Divers mod raises the co-op cap beyond four. Its author says "only the host needs it" and notes that because "Subnautica 2 uses P2P networking, the host handles all connections". Expect a large session to lean hard on the host's PC and upload speed.
• Most mods don't say. When a mod's page doesn't say who needs it, assume everyone in the session should run the same mods at the same versions. That's the safe choice.
• Cheat mods in co-op need consent. The author of the console-enabler mod does "NOT recommend using this in multiplayer unless everyone in the session permits the use of cheats and is playing with the mod installed."
• Branches must match. Everyone must be on the same branch. Experimental and default players can't share a session, and UE4SS doesn't run on Experimental anyway.

Is Modding Allowed?

The game's Terms of Service (effective 21 May 2026) prohibit modifying the game or creating derivative works, and prohibit "unauthorized third-party programs … (including but not limited to hacks, cheats, helpers, bots, scripts, trainers …)". Both clauses carve out anything "permitted under applicable guidelines we may have in effect". At the same time, Unknown Worlds' support team publishes instructions for managing UE4SS mods, and its patch notes address modded players directly. It has also said it "would like to consider official mod support for future releases."

We can't give legal advice. The practical reading is that single-player and consensual co-op modding is widespread and the studio's public communication treats it as a known quantity. Read the Terms yourself if it matters to you.

Can You Put Mods on a Subnautica 2 Server?

No, because there's no Subnautica 2 server to put them on. The Steam app ships Windows-only game files and has no dedicated-server package. Co-op is peer-hosted as described above, so "server mods" don't exist for this game yet.

GameServerKings lists Subnautica 2 as coming soon, but there's nothing to host until Unknown Worlds ships a server build. Until then, Subnautica 2 Release Date: Early Access Is Out, 1.0 Is Years Away covers what has and hasn't been announced about dedicated servers.

Common Questions

Does Subnautica 2 have mod support?

Not official support. The developer says official modding "will not be available initially" and that it would like to consider it later. Community mods work through UE4SS and pak files.

Where do Subnautica 2 mods go?

UE4SS mods go in ...\Binaries\Win64\ue4ss\Mods\ (or WinGDK for PC Game Pass). Pak mods go in Subnautica2\Content\Paks\~mods\.

Why does my game crash after an update?

Almost always outdated mods. Delete dwmapi.dll from Binaries\Win64, clear Content\Paks\~mods\, and launch again. That's the developer's own fix.

Can Xbox players use mods?

No. Mods install into game files on a Windows PC. The PC Game Pass version can be modded; consoles can't.

Do my friends need the same mods to play co-op with me?

For most mods, assume yes. Some host-only mods, like the player-cap mod, say only the host needs them. Check each mod's page.

---

Made with 💜 by GameServerKings