* The map is divided in Biomes, with different lighting and topography
* The biome you land in is called "Safe Shallows", it is recognised by its light blue hue and abundance of coral. As the name indicate, it is very safe: there are no aggressive predators there. There are two defensive creatures, but neither can kill you unless you're low on health
* Health regenerates slowly. The medical kit fabricator in your lifepod slowly provides unlimited health kits
* Your first priority is to get food and water. Water drops faster than food.
* The game does not tell you how to get water, only that it is "non-vegan". There is a specific purple fish swimming around slowly, very easy to catch and in large quantities. Bring one to the fabricator in your lifepod.
* For food, catch other fishes. A raw fish can stay an infinite amount of time in your inventory. A cooked fish rots progressively. A fish cooked with salt ("cured") can also stay an infinite time.
* Salt is rare in the starting area but very plentiful outside.
* You will unlock new crafting recipes by finding and scanning fragments underwater, or blueprint in wrecks. Large wrecks can be explored by entering them if you have the right tools.
* Resources are plentiful but they do not respawn. Progressively you will have to swim further and deeper away to gather what you need.
* When you are in menus (PDA), the game is not paused and your character can be attacked, drown, or starve. Use the full pause menu (with "Esc" on PC) to pause.
* When you are sitted, your food and water do not decrease. Giving you plenty of time to explore menus.

In Subnautica you are not supposed to kill your way through. In fact you have very little means of defending yourself, so the general strategy is to avoid dangerous fauna and to swim away when attacked.

Notable predators are Leviathan-class, which behave differently. See tips below.

* In the starting area, the only thing to be wary of is the Crashfish, a round red fish that, when bothered, will scream and swim full speed and try to explode on you. They are hard to outswim but they don't turn well so if you swim diagonally and cross them they will explode behind you. You find them at the entrance of caves. Once they have left their hideout (and exploded) you can head there to get cave sulfur
* Most aggressive fauna is in fact pretty passive. Agro ranges are short, they lose interest rather fast. However they can surprise you, keep an eye on them at all time.
* You swim faster than most predators if you have fins equipped. It is easy to escape
* Once you have the seaglide, you can outswim all predators as long as you're below the surface.
* Some predators can be temporarily calmed if offered with some fish. But be careful
* Fishes respawn. Larger predators do not.
* One specific early-game predator can be calmed with metal salvage. This can prove useful for some late-game crafting recipes.

The really dangerous beasts are called "Leviathans", which just means they are huge. They are large, fast, and deal heavy damage.

* Leviathan-class predators are found in the far east (around the Aurora wreck), north-east (beyond a very notable landmark), deep in the far north (one 300m deep), deep in the far south (also 300m), and in very large quantities in the far west (your PDA will warn you when you first enter that zone)
* Most Leviathans are below 100m deep. The only exceptions are around the Aurora
* Leviathans can be heard from a great distance, especially reapers. Pay attention to sounds when advancing in an unknown area. If you have a sonar, you can see them more easily
* Leviathans have a wider agro range because they cover huge areas
* Leviathans do not respawn when killed. Good luck, though. It is not recommended to attack one unless you really know what you're doing.

* There is one creature that is passive at the beginning of the game but becomes more and more aggressive as the story progresses. The point where they start to get aggressive is when your PDA suggests you to scan yourself.

* Creatures do not attack bases or the lifepod. But they can attack vehicles.

* The first step to get the story started is to repair the radio in your lifepod.
* You will receive distress signals that give you waypoints on your HUD, pointing to places to reach and explore. These are not timed, you have all your time.
* You can re-enable an explored waypoint in your game menu (PDA)
* None of the events can be altered, the story is linear. Although not all events or places need to be discovered for you to beat the game.
* There is only one timed event and you'll get a big timer once it arrives. It can be missed without influence on the progression but it's a good idea to be there because the sequence is cool.
* At some point you will explore the Aurora wreck but you need to be well-prepared with at least a knife, a laser cutter, repair tool, food and water, fire extinguishers
* At some point you will get a waypoint to a "rendez-vous zone" for survivors. This will lead you to a very peculiar landmark, which you should carefully explore. There are five points of interests, and you should at the very least find a hint that opens a new waypoint to some deeper place
* There are some very deep places to discover and they need some exploration, but some downloaded data gives you the approximate depth.
* Deepest places need you to find entrances to them, but following waypoints and reading the data you download should eventually lead you to one.

* There is an item called a "Beacon" which gives a waypoint on your HUD to an interesting area. This is super duper important. Always carry one. You can disable waypoints in your game menu if you get overloaded
* The further away you go from the start area, the deeper it gets. But you also find more advanced material for your crafting needs
* The edge of the map is an endless void ocean. Your PDA will tell you about an "ecological dead zone" and you won't see the sea floor. Leviathans will spawn and attack you until you turn back. There is literally nothing out there.
* You may find fish eggs. They can be hatched once you unlock the relevant equipment. A very rare egg is needed for the rarest Steam achievement (but not to beat the game)

After some point you will be able to build bases

* Bases can be built underwater, as deep as you want
* Solar panels work underwater, but the deeper you go the worse they are
* As long as your base has energy it produces oxygen automatically. Same goes for vehicles
* The deeper you go, the stronger the pressure on your base so you will need to build things to increase hull integrity.

After some point you will be able to build vehicles. There is a total of 3 vehicles that can be crafted, each with their own strengths. Vehicles are needed for deep exploration. Vehicles are unlocked by scanning relevant fragments or finding blueprints.
The largest of the three vehicles needs you to scan fragments of its building blocks, rather than fragments of the vehicle itself.