Subnautica

What Subnautica is

Subnautica is Unknown Worlds Entertainment's underwater survival game, set on the ocean planet 4546B. Your transport ship breaks up overhead, your lifepod splashes down, and the entire game world is the water around you. No zombies, no firearms, no respawning enemies — just a survival knife, the materials you scavenge, the habitats and vehicles you build, and a quietly excellent science-fiction story about an interstellar plague unfolding beneath the surface.

The original launched in 2018. Subnautica: Below Zero followed in 2021 with a colder, ice-shelf setting. Subnautica 2 was announced for 2026. All three are on Steam, Epic, GOG, PlayStation, Xbox, and Switch — but mods only run on the PC version, and historically the Steam build is the most-tested target.

Why it's so moddable

The PC release is built on Unity and ships its game code as plain .NET assemblies, which makes the modding ceiling relatively low. With the right tooling you can patch existing classes, register entirely new items and recipes, drop in custom 3D assets, or hook into save data. The result is a community that's spent the last several years filling in the bits Unknown Worlds didn't:

• Inventory and storage — denser bins, smart-sort lockers, expanded base storage modules.
• Vehicle behaviour — battery management, light controls, repair mechanics, fast-travel docks.
• Visual polish — VR support, biome retextures, creature reskins.
• Quality of life — first-person crafting, faster scanning, time-of-day toggles, ping clustering.
• Total conversions — Nitrox brings multiplayer; full-content expansions add biomes, vehicles, and storylines.

The toolchain

Two pieces of tooling cover ~95% of Subnautica mods on OpenMods:

1. BepInEx — the bootstrapper. A Unity-focused modding framework that injects into the game process before scripts run, so your mod DLL is loaded alongside the original assemblies. Subnautica's ecosystem targets BepInEx 5.
2. Nautilus — the modding API. Built on top of BepInEx specifically for Subnautica, Nautilus gives typed handlers for items, prefabs, recipes, language strings, encyclopedia entries, save data, and most of the things you'd otherwise have to dig out of the decompiled game by hand. The vast majority of Subnautica mods on OpenMods take a hard dependency on it.

New to all of this? The Getting Started with Subnautica Modding guide walks you through it end to end in about 10 minutes.

What's on OpenMods

Browse the full Subnautica catalogue from the Browse all Subnautica mods button on the right. The grid below is what's most popular right now across the community — storage solutions, lighting overhauls, energy management, VR support, and the Nautilus API itself.