Walkthrough (Below Zero)

Read at own risk This article contains unmarked spoilers. Players new to the game would want to avoid or be cautious toward this article.

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.

Beginning

Research Base Zero

The story starts with Robin waking up in Research Base Zero, where she is stationed. The game instructs you to press Tab 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 W A S D to walk, Left Shift 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 (LMB) to be picked up. PDA entries that are picked up are added to your Databank, which can be accessed by pressing Tab 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.

Open Ocean

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 6×8 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 R 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 LMB. 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.

Sanctuary Zero

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.

Radio Tower 7

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 (LMB) 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, WASD 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. Both of these salvages can be found within the same biome, however before you look for them you will need one vital tool; the Laser Cutter, which allows Robin to cut open damaged doors and containers. Its blueprint is found solely in the Arctic Kelp Caves, either from fragments lying around or by scanning Sea Monkey Nests, which are small round hills covered in netting. Once you have its blueprint, you need to craft it; the recipe is 2 Diamonds, 1 Battery, 1 Titanium, and 1 Crystalline Sulfur. You should know where to find all of these materials except for Diamond, which can be found pretty easily in the Thermal Spires surrounding the Rocket Island.

Once you have the Laser Cutter, begin exploring the biome southeast of the Rocket Island. It is mainly characterized by round rocks spewing purple or pink material, as well as flat blue seabeds and brownish-yellow terrain. This biome is called the Purple Vents. Within the Purple Vents is a large creature known as the Chelicerate, which may end up being the first leviathan creature you encounter. Leviathans are giant creatures which can be extremely dangerous to Robin, even while in vehicles. Fortunately, they are quite dumb and easy to avoid. Continue to explore the Purple Vents until you come across sizeable wrecks; there are two. One contains the Purple Vents Salvage, and is a mess of destroyed junk (on Experimental Mode it is instead a large, rusted engine nacelle that you can enter). The Purple Vents Salvage should be among the junk (or inside the engine nacelle behind a sealed container).

The other salvage is inside of a massive Crashed Ship in the Purple Vents. It may behoove you to bring a Flashlight along, as the ship can be quite dark on the inside. If you have trouble finding the ship, try to stay along the border of the Purple Vents and a green-floored biome called the Lilypad Islands biome. Note that there are two halves of the Crashed Ship; if the half you find is not touching the Purple Vents biome, it is the wrong half. Once you do find the correct location, you need to find a hole on the side of the ship to enter; there are several. Make sure to park your Seatruck near the entrance, and to bring a hefty tank, or even multiple (you can use multiple tanks if you switch them out in your inventory when at 30 seconds of oxygen). Be very careful where you go, as it is easy to get lost and drown inside the ship. You will have to cut open at least one sealed door with the Laser Cutter to find the salvage; go up to the door with your cutter out and hold right click RMB to cut open a hole in the door. The salvage you need is within the engine room of the ship, inside a container that is also sealed shut. Once you have both salvages, head back to the radio tower with them in your inventory and repair the tower by holding the Repair Tool in your hand and hold right click RMB. On the way up to the tower, you may encounter someone in a Prawn Suit. She'll become important later, so remember her.

Debrief

Communications Returned

Once you repair the tower, Sam comes back over the radio and inform Robin that a meteor hit the Vesper and caused communications to fail. Robin's colleague Jeff was in the escape ship that took off at the beginning, and his ship appeared to have sailed off towards an on-land biome called the Glacial Basin. You will go there later, however at the moment Sam ends communications and you are most likely left without anything to do. More will come in an in-game day or two; you can use this opportunity to explore, find new technology, or build the next vehicle; the Prawn Suit.

Mining Site

That scary lady you saw was in a Prawn Suit; a vehicle that can walk along the seabed or above-water. It comes equipped with two modifiable arms and it very resilient to damage. Its blueprint can be found in two locations; the Glacial Basin and the Alterra Mining Site. The latter is slightly more dangerous, however it also contains an arm upgrade for the Prawn Suit, so you want to go there anyway. The entrance to the mining site is southwest of the Rocket Island, about 120 meters down in the Thermal Spires; it is not far from the island. You'll know you found the entrance when you find doors in the wall of the biome. This entrance, however, is too small for the Seatruck to fit through, and it is nearly impossible to get all the way through the mining site on oxygen alone, no matter how much equipment you bring along (save for a network of Pipes; it may work, but it'd be expensive). Rather, you want to bring the Seatruck through the secondary entrance; it is found a short distance from the main entrance. It's in a crevice filled with volcanic geysers. It may seem dangerous to put a Seatruck through a small hole filled with lava and explosions, but actually you can fit through pretty easily.

Once inside, you'll see a large hole in the ground with tracks going deeper, carrying large chunks of ore out of the cavern, though the site is no longer operational. Follow the tracks through the cavern to a platform holding a damaged Prawn Suit. This is a fragment you can scan; all four of the fragments are inside the cavern. By the first fragment is also a Prawn Suit Drill Arm fragment. You need two of these, and they are also inside the cave. A bit deeper within the cave you'll come across an area with the second drill arm fragment, which resembles some sort of loading dock for Prawn Suits. In this area there is a small console by one of the docks, next to which is a Prawn Suit Jump Jet Upgrade. You'll use it when you build your Prawn Suit. In this area is also a Data Box containing the Vehicle Upgrade Console, which is used to upgrade your vehicles. Make sure to pick it up before continuing, as well as scanning the two Prawn Suit fragments nearby.

A very short distance down the cave from the loading bay is a bend; the cavern splits into two parts. The left cave area contains a large Architect Artifact. They are not really needed to progress, but since you're in the area you should take the time to scan it. Artifacts can be found all over Sector Zero, and scanning enough of them will reward you with new technology.

The cave to the right is where the mining site ends. The elevator in the center of the room holds the blueprint for the Headlamp, a wearable Flashlight. Also in the room is the final Prawn Suit fragment. Collect it, and you should have everything you need from the mining site. You can exit from the same way you came in, or through a hole in the ceiling of the final room.

Prawn Suit

Now that you have unlocked the blueprint for the Prawn Suit and the Drill Arm, you can head back to your base or Drop Pod and craft them. The Prawn Suit is crafted in the Mobile Vehicle Bay, and requires 2 Plasteel Ingot, a Power Cell, 1 Enameled Glass, and 3 Lead. Lead and Power Cells are simple; you can look at your blueprints tab for the recipe for Power Cells, and it is easy to craft. Enameled Glass is also easy, and all of its materials you should already know how to find. Plasteel Ingots introduces a new resource: Lithium. Combining it with Titanium Ingots creates an even stronger ingot. Lithium can be found in several biomes, but mostly easily they can be located in the Purple Vents biome from earlier. It can take a while to gather these resources, but it is rewarding. Once you build your Prawn Suit, it will sink to the bottom of the ocean, where you can enter it and start walking around on the ocean floor, with the same controls as you would use when walking on land. You can also control the left and right arms by clicking LMB RMB.

A Prawn Suit's arms is the core element of the vehicle. They can be modified to perform a large range of functions. In the mining site, you scanned the Prawn Suit Drill Arm, which can be used to mine large chunks of ore that you may have noticed in the mining site. To build the Drill Arm, you first need a Moonpool, which is attached to your base. Make sure to build the Moonpool somewhat close to the ground, so you can dock your Prawn Suit in it. Inside the Moonpool, you can build the Vehicle Upgrade Console (whose blueprint you picked up in the mining site) against one of the two smaller walls of the Moonpool. Once built, you can use the small fabricator on the wall by the console to craft the Drill Arm. The console also allows you to modify the name and color of any docked vehicles (you can also dock the Seatruck, and docked vehicles will recharge automatically). Make sure you have enough power in the base to run the upgrade console, as well as generate oxygen. See the Seabases page for power generation options. Both the upgrade console and the drill arm use familiar ingredients for their recipes. Once you have the drill arm, equip it onto your Prawn Suit with the upgrades panel on the side of the suit. It can also be accessed while undocked. Place the drill arm in one of the two middle slots, which represent your left and right arms. Then, you can use the drill arm by holding left or right mouse button. When looking at a large resource deposit, you will be able to drill resources directly into the Prawn Suit's inventory, which can be accessed from the back, on top of the suit just behind the hatch. Such deposits can be found in the mining site or later biomes.

Briefing

By now, Sam should have at some point come back over the radio and asked Robin to keep her informed about the Architect she heard in the research site, however Robin chooses not to reveal that she has since downloaded it into her brain. Sam sends Robin a briefing of the current situation in Sector Zero, showing three missions that can be completed. The first two missions both take place on land, so heading there first is recommended. The PDA should have picked up a signal from Jeff's escape ship and added it to Robin's beacon manager. If not, wait around until it does.

Glacial Basin

Finding Jeff

Head to the signal for the Glacial Basin; you will need to bring your Seatruck. The entrance is deep down, under a thick layer of ice. Once you get to the signal, you will have difficulties bringing your Seatruck through; fortunately, you do not need it in the Basin, so you can leave it there and navigate through the cave until you reach the surface.

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