If you are looking for Update 84 specifically to maintain compatibility with older mods or for speedrunning purposes, you can manually revert your game version using the Steam Console.
If you are playing on a modern platform, the update should be applied automatically without manual intervention. subnautica-update-84-installation-tutorial
: Once the download is complete, Steam will provide a file path (usually under Steam\steamapps\content\app_264710 ). You can move these files to a separate folder to run that specific version. If you are looking for Update 84 specifically
Subnautica was the first major post-launch patch released by Unknown Worlds, primarily focused on quality-of-life improvements, bug fixes, and localization updates. Because it is an official game update, it typically installs automatically through your game launcher. How to Install Update 84 You can move these files to a separate
For a visual walkthrough on how to access and install specific legacy versions of the game, check out this guide:
: Press Win + R and type steam://open/console .