Checkpoint64 has a preset for Subnautica 2: it already knows where the save folder is, backs it up automatically and keeps every version. Everything this site has on Subnautica 2:
Subnautica 2
-
Save file location
Windows:
%LOCALAPPDATA%\Subnautica2\Saved\SaveGames -
Backup guide
Subnautica 2 supports co-op, so a group shares one world — and a game still receiving updates can change what a save has to contain. Checkpoint64 already knows the save path and keeps every version, with a lock so nobody overwrites the run. Free download.
-
Sharing with friends
How to share your Subnautica 2 world with friends, from playing live to taking turns when the host is offline.