Unknown Worlds Entertainment has detailed how co-op progression will work in Subnautica 2. The game uses a save system that allows each player to create their own save from a shared session.
Host migration and save persistence
If the original host leaves, other players can continue progression by becoming the host of a new session. Saves remember the original host's inventory even if other players progress. Building and mission progression is shared among all players.
Solo sessions can be converted to multiplayer and vice versa. Cross-platform progression is also supported.
Unknown Worlds Entertainment has not confirmed a release date or pricing for Subnautica 2.
Source: MP1ST
