You’ve spent hours scouting the perfect safe shallows cove, stocked your starter base with a fabricator, labeled storage lockers, and a grow bed for marble melons, but now you’re running out of horizontal space. Building up (or down) is the obvious solution, but many new players run into frustrating leaks or structural gaps when they try to figure out how to connect 2 levels in Subnautica. I’ve built over 20 multi-story bases across both the original game and Below Zero, so I’ve worked out all the kinks to make this process as smooth as possible, even for players who are still learning the habitat builder’s quirks.
Prep Work You Need to Do Before Connecting Two Levels
Jumping straight into building without prep is the number one reason players end up with flooded bases or wasted titanium. You don’t need fancy rare materials to connect levels, but you do need to make sure your existing base is stable enough to support an extra floor, and that you have all the supplies you need on hand before you start. I always keep a spare stack of titanium ingots in my base storage specifically for expansion projects, so I don’t have to run out mining mid-build.
If you’re building in a deep biome like the Lost River or Active Lava Zone, you’ll also want to have 2-3 reinforcement panels on hand to add to the connector after installation, since higher water pressure puts extra strain on vertical building pieces. You don’t need these for bases shallower than 200m, but it never hurts to keep a few in your inventory just in case.
Step-by-Step Process to Connect 2 Levels in Subnautica
Once you’ve completed your prep work, the actual connection process only takes 3-5 minutes if you follow the steps correctly. The most common mistake new players make here is trying to stack regular base rooms directly on top of each other, which always leaves gaps that cause leaks. The habitat builder has specific pieces for vertical connections, and using them is non-negotiable for a stable, leak-free build.
First, equip your habitat builder and open the base pieces menu. Navigate to the “vertical connectors” tab, not the regular room or compartment tab. Hover over the ceiling tile of your lower level where you want to place the connection, and click to place the vertical connector when the outline is solid green. If the outline is red, move your cursor slightly until it snaps to the center of the ceiling tile—this ensures perfect alignment with the upper level.
Next, go back to the base pieces menu and select the room you want to use for your upper level, whether it’s a multipurpose room, I-compartment, or scanner room. Hover directly over the top of the vertical connector, and wait for the green outline to appear before placing it. Never stack regular base rooms directly on top of each other without a vertical connector, even if the outline looks green at first—these builds almost always leak within a few in-game days as pressure shifts.
Once both the connector and upper room are placed, swim inside the lower level, open the habitat builder menu again, and select the ladder piece. Place it inside the vertical connector, and test it by climbing up to make sure you can move between levels without getting stuck. If the ladder won’t place, check that you don’t have a floor panel or furniture blocking the bottom or top of the connector.
Common Mistakes to Avoid When Connecting Levels
Even experienced players make small mistakes when connecting levels, especially if they’re building in a tricky biome with limited space. One of the most frequent errors I see is using glass floor panels on the level above the connector, which blocks the ladder path and forces you to tear up the floor to fix it. Stick to regular titanium floor panels around the connection point, and save glass panels for the edges of the upper level for scenic views.
Building can get tedious, especially if you have to tear down and rebuild a misaligned connector three times in a row because you weren't paying attention. Many players take 5-minute breaks between construction attempts to reset their focus, so they don't make the same silly alignment errors over and over. Casual players who want a quick, low-stakes distraction to unwind between fixes often play Spin Winner, a fast-paced casual game that fits perfectly into short break windows without pulling you too far away from your base build. Once you're feeling refocused, you can jump back in and finish your connection without issues.
Another common mistake is forgetting to check structural integrity after adding the upper level. Each vertical connector adds a small amount of strain to your base, so if your lower level was already at 90% integrity before the build, the extra weight can push it into the red and cause leaks. Add reinforcement panels to the walls of the lower level if you see any red warning bars after placing the upper level. Always test your connection immediately after building it to catch leaks before they destroy your stored supplies or damage your fabricator.
If you’re building a downward level (like a basement for water filtration or nuclear reactor storage), don’t forget to place the connector on the floor of the upper level instead of the ceiling. The same alignment rules apply, but you’ll want to make sure the lower level is placed high enough off the seabed that it doesn’t clip into terrain, which can also cause leaks.
Creative Connection Ideas for Multi-Story Bases
Once you’ve mastered the basic connection process, you can get creative with your multi-story builds to make them feel more personalized and functional. You don’t have to stick to a single straight ladder in the middle of your base—there are tons of ways to design connections that fit your playstyle and the biome you’re building in.
If you’re using a large multipurpose room as your lower level, you can place two vertical connectors on opposite sides of the ceiling to add two separate upper levels: one for a private bedroom with a view, and one for a research station with scanner rooms and battery chargers. This setup works especially well if you’re playing with friends, as it gives each player their own private space on the upper floors.
For bases in shallow, scenic biomes like the Safe Shallows or Grassy Plateaus, you can use vertical glass connectors instead of regular titanium ones to get a full view of the surrounding reef as you climb between levels. Vertical glass connectors only work in biomes with low pressure, so avoid using them below 150m to prevent unexpected shattering that can flood your entire base.
You can also build a spiral staircase using multiple small vertical connectors and half-width side rooms, which gives your base a more realistic, lived-in feel instead of just a straight utilitarian ladder. You can even place a small counter next to the ladder landing to hold commonly used items like first aid kits, filtered water, or cooked fish, so you don’t have to run to storage every time you need a quick refill.
At the end of the day, learning how to connect 2 levels in Subnautica doesn’t have to be a frustrating process full of leaks and misaligned parts. As long as you do your prep work, use the correct vertical connector pieces, and test your build immediately, you’ll have a functional multi-story base in less than 10 minutes. Don’t be afraid to get creative with your connection points, either—some of my favorite bases have had winding staircases and multiple access points that make exploring every floor feel like a small adventure. Next time you’re running out of space in your starter base, skip the messy horizontal expansion and build up instead.
