Subnautica: Base - how to repair? Subnautica Guide and Walkthrough

The endurance (hull integrity) of your base is defined by points. Initially, a base has 10 points of endurance. Each new construction element, corridor, scanner room, and such, added to the structure will subtract a number of points from integrity. If you expand your base without any strengthening elements, the structure will begin to crack, and your base will spring leaks.

Foundations and reinforcements will help you increase the hull integrity of your base.

Simply patching the holes won't do. For each hole you plug a new one will appear. To prevent this from happening, you'll need to strengthen the structure of the base. To do this, use wall reinforcements or foundations. These elements will add points to the hull integrity of your base, keeping it above 0.

Once the hull integrity of your base drops below 0, hull breaches will develop.

Once your base has regained positive integrity, you can proceed with the repairs. To do so, patch the holes in the hull using the repair tool. When you're done, the base computer will inform you that the water is being drained.

Remember that a corridor may remove wall reinforcements. You'll lose the integrity both for a new structural element and for removing the reinforcement. You need to plan your structure beforehand and place reinforcements where nothing else will be built.