Walkthrough (Below Zero)

This page serves as a full-game survival mode walkthrough of Subnautica: Below Zero. It also contains gameplay tips and helpful pointers for successfully mastering the oceans. Keep in mind that this page will have spoilers, as it also summarizes the events as you follow along the story. Note that if at any point in the playthrough you become unable to progress due to a bug, check Console Commands to see if any commands can help.

Background
You play as Robin Goodall, a contracted xeno-linguist for Alterra Corporation on the planet 4546B. Robin's job is to investigate the nearby Almanac ruins to better understand the aliens' culture and technology. Robin has one coworker on site, Jo Jeffreys, as well as her sister, Sam Goodall, who provides orders and monitors Robin from the orbital station, Vesper Station.

Research Base Zero
The story starts with Robin waking up in Research Base Zero, where she is stationed. The game instructs you to press to both turn off the alarm clock and close the PDA, which is an essential tool in Subnautica: Below Zero. After turning on the alarm clock, you gain control of Robin. You can use    to walk,  to sprint, and move your mouse to look around. The first thing you may notice is a blue pad on the shelf you are facing; this is a PDA entry, which can be interacted with by clicking to be picked up. PDA entries that are picked up are added to your Databank, which can be accessed by pressing again to open your PDA and navigating to the Databank tab at the top. There are several other entries available in the research base, but none of them are integral to progression, and can be safely ignored.

Once Robin is awake, you can exit the room through the bulkhead door by interacting with it. There is quite a large area to explore with PDA entries and a Snowman, but none of it is mandatory to continue the story. To progress, exit the base through another bulkhead door (there are four exits) and head towards the canyon on the left.

Alien Research Base Zero
Once Robin has exited the base, Sam will come over the radio and inform Robin that her colleague, Jo Jeffreys, is missing. Head towards the canyon on the left, which is filled with large Thermal Lilies and leads to a big ice cave. Follow the cave to the massive open room with a tall, alien structure on the opposite wall. This is Alien Research Site Zero, one of the most important elements to the story. The structure has an opening on the ground, which is actually two open doorways. Head through the first doorway and the second will suddenly lock with a forcefield. An alien voice will speak to Robin cryptically, asking her to surrender. Upon learning this, Sam will warn Robin that an electrical storm is approaching, and thunder will crackle in the distance. Head back out through the way you came (not through the tunnel on the left). Upon reaching the cave entrance, lightning will strike the mountain, covering the path you came from but opening another up a rocky slope on the left. Go up the ramp of rocks to get to the Frozen River, which you can follow all the way back to the lake by Research Base Zero.

When you reach the lake, a huge avalanche will come crashing down, engulfing Research Base Zero and knocking the radio transmission tower into the lake, which will shatter the ice and cause the ladder to fall, as well as forcing Robin into the water. Having no other way out of the lake, you must go underwater through a tunnel to get to safety. At this point, your PDA reboots into emergency mode, meaning your Oxygen, Health, Food, and Water bars will appear at the bottom left of the screen. We'll talk more about the bars in the next section, but the oxygen bar is a timer for how long you have left before needing air. If you run out of oxygen, Robin will black out and you will be forced back to a previous location, losing some items. The bar counts in seconds of oxygen remaining. When you get to a location with air, the bar refills very quickly. As you swim through the tunnel, you will get to an Oxygen Plant, which can refill 30 seconds of oxygen by interacting with it, after which it will retract into itself. Shortly after the plant is an air pocket in the ceiling of the tunnel, and the exit of the tunnel follows soon after.

Stranded
The tunnel exits into the main area of gameplay, known as Sector Zero. The exact biome you are now in is the Shallow Twisty Bridges. At this point, your food bar should be about half. Food and water are two core gameplay threats that need to be managed constantly. To refill food and water, Robin must eat cooked fish, which can be made using caught fish, eat Cured Fish, which are made from fish and Salt Deposits, and drink Filtered Water, which can be crafted using Bladderfish. Also present is the health bar, which monitors how much damage you can take before dying. Damage usually comes from predatory fauna or flora, though it can also be caused by fall damage and excessive heat. Healing requires the use of First Aid Kits.

Shortly after exiting the tunnel, Sam will contact Robin again and send down a Drop Pod, a safe location for Robin to store and craft items. Inside the Drop Pod is a 6x8 storage locker and a Fabricator, one of the most essential crafting machines in the game. The Fabricator has four tabs: Resources, for crafting items that are used to craft final products; Sustenance, for crafting food and water; Personal, for crafting Equipment and Tools; and Deployables, useful items that are placed into the world and have a handy effect. Right now, there are three items of vital importance to craft: the Survival Knife, the Scanner, and the Standard O₂ Tank.

Important Tools
The quickest tool to craft is the Scanner. Its recipe is one Battery and one Titanium. Titanium can be acquired by breaking open Limestone Outcrops, which litter the floor and walls of many biomes, including the one you are currently in. The outcrops also drop Copper Ore, which is required to craft batteries. The other resources needed for batteries are two Ribbon Plants, which are small, narrow, yellow and green plants generally found in the caves of the Shallow Twisty Bridges. Once you have all the items you need, return to the Drop Pod to crab the Scanner. The Scanner allows you to scan fauna, flora, rocks, and most importantly, Fragments. Fragments are broken pieces of technology that litter the floors of almost every biome. Each biome has a different array of fragments. One very useful technology that can be scanned in the Shallow Twisty Bridges is the Seaglide, which greatly increases your movement speed. Note that it and the Scanner require a charged battery to operate. If your tool runs out of power, simply craft another battery and replace it by pressing while holding the tool.

The next important item is the Survival Knife. The knife allows you to collect certain resources and fight off aggressive life forms should the need arise. The knife's recipe is one Titanium and one Silicone Rubber. Silicone rubber can be crafted by harvesting a Seed Cluster in the Arctic Kelp Forest. One of the forests can be found in the direction away from the tunnel. Once you make your way there, the seed clusters are bright yellow bulbs hanging off the tall Creepvines. It is prudent to harvest as many as you can carry, as you will need more later. Once you have everything you need, head back to the Drop Pod to fabricate the knife.

The third item that is necessary to craft is the Standard O₂ Tank. The tank increases your total oxygen, allowing you to stay underwater much longer. Its crafting recipe is two Titanium and a Fiber Mesh. Fiber mesh is crafted using two Creepvine Samples, which can be acquired by using the Survival Knife on a Creepvine in the Arctic Kelp Forest. To use the knife, simply equip it using the number keys and then click. Once you craft the tank back at the Drop Pod, several more crafting recipes will be unlocked and after a bit, Sam will contact Robin again.

Supplies
Sam gives Robin the location of an emergency supply cache in the Arctic Kelp Forest. The supply cache contains the blueprint for the Compass, which puts a compass on the player's HUD. Something you should take the time to craft is the High Capacity O₂ Tank, an upgraded version of the Standard O₂ Tank you previously crafted. Though not absolutely necessary to progress, if you are an unexperienced player it is recommended to craft this upgrade. The blueprint for it can be found in the Twisty Bridges; just explore until you find it, or skip to the next section if you can go without. Its recipe calls for four Titanium, two Glass, and one Silver Ore. Glass is crafted by combining two Quartz. You may have already seen quartz; it is a white, crystalline object found on the floors of the Shallow Twisty Bridges and the barren Sparse Arctic (which you passed through to find the cache). In total, you need four quartz for the tank. Silver ore is more tricky to find; it is available in the Arctic Kelp Caves and the Twisty Bridges. The former is safer, as it has no predators, but can be easy to get lost in. It is also significantly easier to find the Twisty Bridges, as they are just trenches surrounded by some parts of the Shallow Twisty Bridges, whereas Arctic Kelp Caves entrances are few. Whichever you decide, you must look for Silver Outcrops, which are grey rocks protruding from the surface of walls. Once you have everything you need, head back to the Drop Pod to craft the tank. Remember to take off your old tank in order to craft the new one.

Finding the Sanctuary
At some point, Sam will tell Robin that there is a nearby alien sanctuary that she should explore. The sanctuary is located deep in the Twisty Bridges, at a depth of 180m. You can find the entrance by going farther away from the Drop Pod, opposite the direction of the tunnel. Once you get near the sanctuary, you may see some alien pillars, and Sam notify Robin that she is close. Follow the pillars to find the sanctuary, which is another large alien structure with a wide, square opening. Going through the opening will take you out of the water and back onto your feet.

The Download
The first thing in front of you is the cave of the sanctuary. Follow the rocky path to get to the inner sanctuary, which is marked by more alien structures. Along the way, a voice will speak to Robin, who Robin attempts to fruitlessly converse with. Inside the inner sanctuary is a large, open room with a giant cube-like structure in the center. Go around the cube and up the ramp to find a green hologram. Interacting with the hologram initiates a cutscene in which an Almanac consciousness is downloaded into Robin's brain. Once Robin regains consciousness, she and the alien will argue with each other, Robin wanting the forcefield opened and the alien wanting to be put back into the cube. The alien will eventually fail to continue and hibernate inside Robin's brain, opening the forcefield. You can now exit the sanctuary.

Bioscanner
Upon leaving the cave, Sam warns Robin that her biometrics readings are strange. She will ask Robin to send a sample using a Bioscanner that she sends down in a Supply Crate. Simply acquire the bioscanner, at which point the alien will wake up and warn Robin that if she sends the biosample, Alterra will arrest her. He offers to mask his presence. Use the bioscanner to acquire a Biosample. After this is done, Sam will ask Robin to send the biosample up in the Exchanger Rocket on the Rocket Island, which is marked by a new signal. Make your way to the island and go through the caves and up the slopes to reach the rocket.

Launching the Biosample
Observation of the rocket will reveal that it is damaged. You need to craft a Repair Tool, which has a recipe of one Silicone Rubber, one Titanium, and one Crystalline Sulfur. The sulfur can be acquired back in the Twisty Bridges or on the Rocket Island itself. Look for protrusions on the walls of the Twisty Bridges that open up when you get close. When you approach them, a Crashfish will swim out and chase you; make sure to swim away as fast as possible as it will explode after a few seconds. Once the fish is dead, you can return to its home, the Sulfur Plant, and grab a crystalline sulfur from it. Crystalline Sulfur can always be located in the caves on the Rocket Island. Craft the repair tool and return to the rocket. Its damaged area is a large black rectangle with wires hanging loose. Equip the repair tool and hold right click to repair the rocket. Once the rocket is fully fixed, head to the central orange covering to place the biosample inside the rocket. Then, return to the controls at the nose of the rocket to launch it towards Vesper Station.

Habitat Builder
After sending up the biosample, Sam will send down a Habitat Builder for Robin to use. The habitat builder allows Robin to build Seabases in the water or on land. Seabases allow you to have a base away from the Drop Pod, which can contain storage and useful facilities such as a Fabricator. See Seabases and Hull Integrity for more information.

Sea Truck
At this point, the story will force you into deeper sections of the region. It is highly recommended to acquire the Sea Truck, a submarine that can be modified to suit your needs using attachable and detachable modules. The first step is finding its Fragments, which can be found in the Twisty Bridges and Thermal Spires. They are more easily located in the Thermal Spires, the biome immediately surrounding the Rocket Island. Once you scan three, you'll unlock the Sea Truck; however, you also need the Mobile Vehicle Bay, which allows you to build vehicles. These fragments (you need three) can be found in the Twisty Bridges as well, however are more common in the Arctic Kelp Caves, which are large caves whose entrances are in the Arctic Kelp Forest. Be prudent when diving here; Sea Monkeys can steal your held item, and it may be difficult to find your way out.

Once you have both blueprints, it's time to craft both. The Mobile Vehicle Bay calls for one Titanium Ingot, one Lubricant, and one Power Cell. All three are easily crafted; the Titanium Ingot simply requires ten Titanium, and the Power Cell needs two Batteries and a Silicone Rubber, which you have crafted before. Once you've crafted the bay, simply equip it and drop it in somewhat deep water and it'll float to the surface and open. Climb on by clicking it and click again to open the crafting menu.

Next, you need to craft the Sea Truck itself, which is more difficult to acquire the ingredients for. It calls for another Titanium Ingot, five Advanced Wiring Kits, two Glass, and three Lead. Titanium Ingot and Glass are simple; the rest, however, should be new to you. Advanced Wiring Kits require a Wiring Kit (which require two Silver Ore), two Gold, and a Computer Chip each. This means you need to gather all of the ingredients for five Advanced Wiring Kits, which totals out to ten Silver, fifteen Gold, ten Table Coral Samples, and ten Copper Ore (for the Copper Wire of the Computer Chips). Most of these you've seen before; they can be found from nodes all over the region. Table Coral Samples, however, are quite rare. They can be found by cutting Table Corals, which are flat corals found in the Twisty Bridges. They are rare, so keep looking. After you manage to find those, you need Lead. They can be found quite easily from Lead Outcrops in the Thermal Spires and Twisty Bridges. As usual, the former is more reliable.

If you've managed to get all the materials needed to craft the Sea Truck, head back to you Mobile Vehicle Bay, or drop it back down if you picked it up. Climb on and craft the Sea Truck. After a short animation, it'll be dropped in the water in front of you. You can enter it through a hatch on the roof. The Sea Truck runs on Power Cells, which need to be charged up in Power Cell Chargers; alternatively, you can build a Moonpool to charge your Sea Truck while docked. The Sea Truck is controlled much in the same way as the player; mouse to look around, to move. Pressing backward will also turn on a rearview mirror, which can be disabled by pressing forward again. The main feature of the Sea Truck is modularity; using Sea Truck modules, you can pick and choose what your Sea Truck can do, from storage to teleportation. It is also upgradeable using upgrades crafted in the Sea Truck Fabricator Module. See the Sea Truck page for more information on modules and upgrades.

That's the end of finished content in Subnautica: Below Zero.