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 xenologist for Alterra Corporation on the planet 4546B. Robin's job is to investigate the nearby Architect ruins to better understand the aliens' culture and technology. Robin has one coworker on site, Serik Jevov, 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 confirm Sam's call and close the PDA, which is an essential tool in Subnautica: Below Zero. After confirming the call, you gain control of Robin. You can use    to walk,  to sprint, and move your mouse to look around. After closing the PDA, Sam informs Robin that there is a meteor storm happening and that she needs to go find Serik, who is at the nearby Architect ruins. Something you may notice in the room 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.

Once Robin is awake, you can exit the room through the bulkhead door by interacting with it. To progress, exit the base through another bulkhead door and head towards the canyon on the left.

Alien Research Base Zero
Once Robin has exited the base, 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 suddenly locks with a forcefield. An alien voice speaks to Robin cryptically, telling her that Jeff (Serik Jevov's nickname) woke them up, followed by a meteor striking the mountain above. Despite the cryptic message, Sam urges Robin to evacuate the area. Head back out through the way you came (not through the tunnel on the left). Upon reaching the cave entrance, a meteor strikes 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. As you descend the river, Robin's escape ship will take off, much to her and her sister's alarm. Continue towards the lake as meteors crash into the ground around Robin.

When you reach the lake, a huge avalanche comes crashing down, engulfing Research Base Zero and knocking the radio transmission tower into the lake, causing communications with Sam to end, shattering the ice, and causing 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. Swim to the end of the tunnel to progress with the story.

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 contacts Robin again and sends down a Drop Pod, a safe location for Robin to store and craft items, though immediately after a meteor strikes the Vesper and communications again end. Inside the Drop Pod is a 6&times;8 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 craft 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 many biomes. Each biome has a different array of fragments. One very useful piece of 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, which resemble real-life kelp. 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.

Supplies
After entering the Drop Pod for the first time, the PDA locates an emergency supply cache in the Arctic Kelp Forest and adds the beacon to Robin's PDA. The supply cache contains the blueprint for the Compass, which puts a compass on the player's HUD. The beacon for the cache can be turned off in the beacons tab of the PDA. 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, the PDA will notify 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. 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 speaks to Robin, informing her that "a storage capacity is found on her person". The entrance to the inner sanctuary contains three Ion Cubes, which you may want to pick up as they are not very common. 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 Architect consciousness is downloaded into Robin's brain. Once Robin regains consciousness, she and the alien talks with each other, both of them surprised that the voice is now in her head. The alien hibernates inside Robin's brain while it thinks of a solution for their situation. You can now exit the sanctuary.

The Rocket Island
When Robin re-enters the Drop Pod, the voice tells her that someone's memory data was lost during the download, and it must continue to hibernate. Before it does so, Robin asks for its name, to which the voice concedes that Robin may call it Al-An. After this exchange, the next step in the story is to head to the Rocket Island, a large island in the center of Sector Zero that holds the Exchanger Rocket, a vehicle vital for sending and receiving things from the Vesper, as well as Radio Tower 7, the primary communications tower for the island which, in Robin's case, will serve as a backup radio. Head towards the island, which can be seen from a fair distance to the South (away from the tunnel and mountains). The PDA will notify Robin about the radio tower as she nears the island.

When you get to the island, you must then climb it towards the top where the tower resides. Go through the caves to reach it. The island is also a good opportunity to introduce the Temperature mechanic. When Robin is outside of the water, she will become colder and colder without sources of heat to warm her up. Going too long without heat will cause Robin to die of hypothermia. On the Rocket Island, Thermal Lilies provide a very convenient source of heat that makes surviving the island very easy.

Rocket Island Base
Once at the top of the island, you will most likely see the Rocket Island Base before seeing the tower. By the base is a supply crate containing a Habitat Builder. 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.

There are also certain scannable objects in the base. Most do not have a use other than vanity, however two specific objects stick out as extremely useful; the Multipurpose Room and the Modification Station. The room can be scanned from the outside (it is the large round room, there are two of them), and the Modification Station is found inside the bedroom of the base. It can be used to build upgrades to certain equipment and tools, such as the knife and the oxygen tank. After scanning everything you need or want, exit the base and head up the stairs in front of you to the radio tower.

Repairs Required
Observation of the radio tower reveals that it is damaged, and that it requires two specific components to be repaired. First, 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 (the latter is a much easier source). 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 also be located in the caves on the Rocket Island. You should now be able to craft the Repair Tool, however it is not the only item required to repair the radio tower.

Seatruck
At this point, the story will force you into deeper sections of the region. It is highly recommended to acquire the Seatruck, 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 pieces, you'll unlock the Seatruck; 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 they 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 Seatruck itself, which is more difficult to acquire the ingredients for. It calls for another Titanium Ingot, two 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. 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, and pay special attention to the walls of the biome. 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.

Once you've managed to get all the materials needed to craft the Seatruck, head back to your Mobile Vehicle Bay, or drop it back down if you picked it up. Climb on and craft the Seatruck. 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 Seatruck runs on Power Cells, which need to be charged up in Power Cell Chargers; alternatively, you can build a Moonpool to charge your Seatruck while docked. The Seatruck 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 Seatruck modules, you can pick and choose what your Seatruck can do, from storage to teleportation. It is also upgradeable using upgrades crafted in the Seatruck Fabricator Module. The modules and upgrades must both be unlocked through more exploration, though some upgrades are unlocked by default. See the Seatruck page for more information on modules and upgrades.

Salvaging
Radio Tower 7 also requires two important components; the Purple Vents Salvage and the Ship Wreck Salvage.

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