If you’re just starting a new game of Subnautica, you’ll quickly find that keeping up with your depleting hunger and thirst bars is critical to survival.
First mission outside of the Lifepod: Grab lots of Bladderfish
Over time, your Food and H2O meters will deplete from 100 down to 0, but the H2O meter will drop much more quickly than Food does. During all phases of the game, but especially during the early part of the game, staying hydrated needs to be a top priority. Fortunately, water doesn’t spoil and you have some storage space to make use of. Keeping it stocked with bottles of water will help keep thirst from becoming an emergency.
Your only option for creating water at this stage is to process a Bladderfish to create Filtered Water (H2O: +20) using the Fabricator. They can be found all around your Lifepod without having to venture very far.
Cook only what you can eat
For the first part of the game, your primary source of food will be fish. Once you catch a fish by grabbing it out of the water, it will go into your inventory and will remain alive and unspoiled indefinitely, even if placed in the Storage Compartment. In order to get the full nutritional value from the fish, you will always want to cook it first using the Fabricator. However once you’ve cooked a fish it will begin to spoil almost immediately if you don’t eat it right away, so cook only what you need and store the rest of them uncooked.
Prioritizing edible fish
Your lifepod has landed in a spot that is teeming with several kinds of edible fish Of the edible fish found in the waters around your Lifepod, Peepers have the largest food value (+32 Food, +5 H2O.) Holefish and Boomerang fish supply +21 Food, +3 H2O when cooked, Hoverfish and Hoopfish +23 Food, +3 H2O, and Garryfish +13 Food, +5 H2O. You could cook Bladderfish to eat if necessary, but they only supply +16 Food, +4 H2O and, with the endless supply of Peepers and Boomerang fish around it’s best to use the Bladderfish only for producing Filtered Water.