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.
Which storefront context matters
Documented Subnautica PC launchers/storefronts: 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. The active storefront/account should be identified before any restore because cloud and local storage may not use the same path or container across editions.
Documented cloud behavior
Cloud support depends on storefront. The local slot directory should still be backed up before game updates, mods, or migration. Cloud synchronization is useful for continuity, but it can also turn a restore into a conflict-resolution event. Let synchronization settle before making a manual backup, and keep an offline copy outside any folder monitored by the launcher or operating-system sync service.
Local save roots still matter
The researched local save boundary 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 file or folder pattern is slot0000, slot0001, … save directories. A cloud-enabled game still has concrete local data involved in ordinary play, and that local context is what you need when identifying which copy was modified most recently.
Avoid accidental overwrite loops
Copy complete slot directories or the entire SavedGames folder. Do not back up only the most obvious binary file inside a slot. When restoring, close the game and launcher, preserve both the current local copy and the backup you want to test, then place the intended data in the matching profile/storefront location. Do not repeatedly open the game between different copies without noting which side the cloud client selected.
Compatibility and conflict checks
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. If progress disappears or rolls back, If the expected SNAppData directory is empty, identify the storefront and check the documented Epic LocalLow path. Keep older slot copies intact while diagnosing. Resolve identity/path/cloud questions first. A cloud conflict is not proof that the save itself is corrupt, and a successful upload is not proof that files from another storefront are compatible.
Verification context: Standard Windows, Epic, macOS, and Steam Play locations were reviewed against current PCGamingWiki coverage.