Press the menu button, then hit the save option. Zero does not save your game. When you die, you return to your base or vehicle without saving the game, as Below Zero does not support Quick Resume.
You can't load when you play either, so you have to go to the main menu then press play and choose the saved game.
You have only one save space per game, but you can have multiple games.
After reading this article on how to save your game to Subnautica Below Zero, we hope that you can handle saving your game in a way that you get the best out of it.
Platform(s):
Microsoft Windows PC, MacOS, Nintendo Switch, PlayStation 4 PS4, PlayStation 5 PS5, Xbox One, Xbox Series X/S