Getting Started with Subnautica Modding

What you need before you start

This guide assumes:

• A PC copy of Subnautica (Steam, Epic, GOG, or Xbox app — any storefront, as long as it's the PC build, not console).
• About 10 minutes.
• Permission to write files inside the game's installation folder.

You don't need Visual Studio, you don't need Unity, you don't need any compiler. We're installing mods, not building them — that's a different guide.

Step 1 — Get a Subnautica-flavoured BepInEx pack

BepInEx is the bootstrapper that loads mods into the game. Subnautica needs a build that's patched for it — not the generic BepInEx 5 release from the upstream repo.

The community ships pre-configured packs:

• For Subnautica (the original): grab the latest Nautilus Pack (sometimes called "BepInEx Pack for Subnautica") from the Nautilus releases page. It bundles BepInEx 5 + Nautilus + the right patches in a single zip.
• For Subnautica: Below Zero: same source, separate release artifact. Check the release notes for which file targets which game.

Don't grab raw BepInEx from the upstream BepInEx repo. The Subnautica community ships patched builds, and a mismatched bootstrapper either won't load mods or will crash the game on launch.

Step 2 — Drop it into the game folder

1. Close the game completely. Don't let Steam re-launch it during install.
2. Find the game folder. In Steam: right-click Subnautica → Manage → Browse local files. You should be sitting in a folder that contains Subnautica.exe (or SubnauticaZero.exe for Below Zero).
3. Extract the downloaded zip directly into that folder, merging with what's already there. You should now have a BepInEx/ subfolder, a doorstop_config.ini, and a winhttp.dll sitting next to the game executable.
4. Done. Don't move anything around.

Step 3 — Verify BepInEx loaded

Launch the game once via Steam. After it reaches the main menu, quit out.

Open …\Subnautica\BepInEx\LogOutput.log in any text editor. The first few lines should look something like:

[Info   :   BepInEx] BepInEx 5.x.x.x - Subnautica
[Info   :   BepInEx] Running under Unity v2019.x.x

If you see that, BepInEx is alive. If LogOutput.log doesn't exist, the bootstrapper didn't load — confirm winhttp.dll is in the same folder as Subnautica.exe, and that you didn't accidentally set a Steam launch option like -no-doorstop.

Step 4 — Install your first mod

Subnautica mods live under …\Subnautica\BepInEx\plugins\. Most mods ship as a small zip with one or two .dll files and a config.

The hand-driven way:

1. Pick a mod on OpenMods. For your first one, choose something low-risk — a storage tweak, a small QoL fix, a config tool.
2. Download the latest release zip from the mod's page.
3. Extract into …\Subnautica\BepInEx\plugins\. Most mods want their own subfolder (e.g. plugins\StorageSolution\); the mod's README on its page tells you the layout it expects.
4. Launch the game.

If it loaded, you'll see a line in LogOutput.log like [Info: BepInEx] Loading [YourMod 1.0.0].

The automated way:

Install OpenMods Manager — the desktop companion. Once it's connected to your OpenMods account, you click Install on any mod page, the manager downloads the right release, reads its install.json manifest, and drops every file into the right destination automatically. Updates and uninstalls work the same way through the manager. For most players this is the right answer.

Step 5 — Common pitfalls

• "My mod doesn't show up in-game." Check LogOutput.log for errors. A MissingMethodException usually means the mod was built against a different game version — make sure the mod's listed compatibility on OpenMods matches what you're running.
• "The game crashes on the title screen." Almost always a broken dependency. Most plugins need Nautilus and refuse to load without it. Make sure Nautilus.dll is in BepInEx\plugins\Nautilus\ before any other mod, and don't have two copies of it.
• "Steam updated the game and now nothing works." A game patch occasionally moves classes around. Wait a few days — most popular mods get a hotfix release once the community confirms the breakage on Discord.
• "I want to uninstall." Either delete the mod's folder from BepInEx\plugins\, or use OpenMods Manager's Uninstall button (which uses the recorded install.json manifest to clean up exactly what it added).

Step 6 — Where to go next

You've got a working modded game. Natural next steps:

• Browse the full Subnautica catalogue on OpenMods.
• Skim the .openmods/ folder spec if you start thinking about publishing your own mod.
• Join the Subnautica Modding Discord — that's where troubleshooting threads live and where most mod authors hang out.

Once you have five or six mods stacked, the install.json spec starts mattering: it's the mechanism that lets the OpenMods Manager keep everyone's installs reproducible. Worth a quick read before you go too deep.