Subnautica’s save unit is a slot directory. Each slot contains several records describing world and player state, which means a backup made from one selected file can be incomplete. The safest procedure is to close the game and copy the entire `SavedGames` directory or the complete slot you care about. Storefront matters because the base path can change—particularly between the standard game directory and the Epic LocalLow location.
Choose the correct backup boundary
For Subnautica, the researched PC save location is Windows: Standard Windows: <path-to-game>SNAppDataSavedGames
Epic: %USERPROFILE%AppDataLocalLowUnknown WorldsSubnauticaSubnauticaSavedGames | macOS: $HOME/Library/Application Support/unity.Unknown Worlds.Subnautica/Subnautica/SavedGames | Linux / Steam Play: Steam Play: <SteamLibrary-folder>/steamapps/compatdata/264710/pfx/. The known save file or folder pattern is slot0000, slot0001, … save directories. Copy complete slot directories or the entire SavedGames folder. Do not back up only the most obvious binary file inside a slot. Copying the complete documented save boundary is safer than selecting one visually obvious file, because companion metadata, indexes, backups, or multiple slots can be required together.
Make an offline copy before changing anything
Close the game first, wait for the active launcher to finish writing, then copy the save data to a separate folder that the game and sync client do not watch. Label the copy with the game, storefront, profile, and date. Documented launcher context: Steam, Epic Games Launcher, Microsoft Store / Xbox app. PCGamingWiki documents different Windows locations for standard installs and Epic. Microsoft Store packaging should be treated separately when the standard SNAppData path is absent.
Account for cloud saves
Cloud support depends on storefront. The local slot directory should still be backed up before game updates, mods, or migration. Before restoring an older backup, decide which copy should win. If the game or launcher starts while an older manual copy is in place, synchronization can replace it before you confirm that it works. Keep the untouched backup outside the live save path until the restored progress has been opened and saved normally.
Restore without changing format assumptions
Subnautica uses slot directories rather than one portable save file. A slot contains multiple binary/metadata records, so preserving the full slot folder is safer than selecting one .bin file. Compatibility note: A slot folder is a coordinated set of files. Mixing parts from different slot revisions can create a state that was never produced by the game. Restore into the matching storefront/profile context whenever possible. Do not rename a save extension, move a folder into a different container type, or assume a console/mobile copy is equivalent unless a tested migration path specifically says so.
Recovery fallback
If the expected SNAppData directory is empty, identify the storefront and check the documented Epic LocalLow path. Keep older slot copies intact while diagnosing. If the restored copy fails, put the untouched original back first. Then compare location, account/profile, cloud state, and the full directory structure before trying a different backup. The objective is reversible recovery, not repeated destructive experiments on the only copy.
Verification context: Standard Windows, Epic, macOS, and Steam Play locations were reviewed against current PCGamingWiki coverage.