If you’ve ever cut an exploration run short because your Seatruck was too slow to outrun a Squidshark, or drained its battery halfway to the Koppa Mining Site, you know how frustrating early-game travel in Below Zero can be. The Subnautica Below Zero Mercury 2 upgrade fixes almost all of those pain points, if you know where to find it and how to get the most out of it. I’ve put 120+ hours into Below Zero playthroughs across 3 separate saves, and I never make it past the first three in-game days without prioritizing this upgrade. It changes the entire flow of the game for the better.
What Is the Subnautica Below Zero Mercury 2 Upgrade, Exactly?
The Mercury 2 is the tier 2 engine upgrade for your Seatruck, replacing the default low-power Mercury 1 engine that comes with the base cab. Unlike depth upgrades that let you dive deeper, or hull upgrades that reduce damage, the Mercury 2 is built entirely for better travel performance, and it delivers on that promise in big ways.
The most notable benefits include 30% higher top speed even when you’re hauling 3+ attached modules like a fabricator or storage unit, and 25% lower power consumption per minute of travel. That means you can go twice as far between charging stops, even with a full load of modules. It works at every depth your Seatruck hull is rated for, with no extra depth penalty, so you don’t have to worry about swapping it out when you unlock higher depth upgrades later in the game.
A lot of new players confuse the Mercury 2 with the Seatruck jump jet upgrade, but they serve totally different purposes. The jump jet lets you launch your Seatruck out of the water for short bursts, which is great for navigating icy shorelines, but it doesn’t help with underwater travel speed or battery life at all. If you have to pick one upgrade first, go for the Mercury 2 every time.
Exact Locations to Find the Mercury 2 Data Box
You can’t craft the Mercury 2 until you scan its blueprint from an orange data box found in the open world. There are three confirmed spawn locations across the map, but the East Arctic Biome spawn is by far the easiest to reach, even with basic early-game gear. You don’t need a depth upgrade or even a Seatruck to get it, just a sea glide, a standard oxygen tank, and a scanner.
To get the East Arctic blueprint, follow these simple steps:
- Head east from your initial drop pod until you spot floating ice chunks and a visible thermal vent plume on your sonar display
- Dive to 170-190m, keeping an eye out for a small broken Seatruck section half-buried in the sandy seabed, near a cluster of acid mushrooms
- Look for the orange data box inside the open cabin of the wreck; scan it for 10 seconds to unlock the Mercury 2 blueprint permanently for your save
If you’re already exploring the Glacial Basin for the Phi Robotics Center, you can also find a second data box under the ice, near the cave entrance that leads to the basin’s underwater section. Just be careful if you take this route, as Ice Worms spawn frequently in the shallow ice areas above, and they can one-shot you if you’re not paying attention. Bring a stasis rifle if you have one, or stick to the East Arctic spawn if you’re still in early game.
Crafting Requirements and Installation Steps
Once you have the blueprint unlocked, you can craft the Mercury 2 at any Seatruck fabricator module, or at a base fabricator if you have the upgrade console built. The crafting recipe is manageable even for early-game players, as none of the materials require late-game exploration to find.
You’ll need the following materials to craft one Mercury 2 upgrade: 2 Lithium, 3 Titanium Ingots, 1 Advanced Wiring Kit, and 2 Magnetite. Lithium is easy to find in the Purple Vents biome, just a short trip southwest of the drop pod. Titanium Ingots are crafted from 10 Titanium each, which you can get from scraping limestone outcrops all over the shallow starting areas. Magnetite spawns in small clusters in the Koppa Mining Site, or along the walls of the Glacial Basin underwater caves, and the Advanced Wiring Kit just needs 2 Copper Ore and 1 Silicone Rubber to make.
Installation is straightforward. Once you’ve crafted the upgrade, swim to the back of your Seatruck cab, where the engine is located, and open the upgrade panel by interacting with the small port on the left side of the engine. Drag the Mercury 2 from your inventory into the open upgrade slot, and it will immediately replace the default Mercury 1 engine. You can remove it later if you want to swap it for a different upgrade, but you probably won’t want to once you feel the difference in speed and battery life.
Pro Tips to Maximize Your Mercury 2 Performance
The Mercury 2 is already a huge upgrade on its own, but there are a few small tricks you can use to get even more value out of it, especially if you do a lot of long-distance exploration. I’ve tested all of these across multiple playthroughs, and they’ve saved me hours of travel time and lost resources.
First, always pair the Mercury 2 with the Seatruck Depth Upgrade MK2 as soon as you can. The extra speed and battery life don’t help much if you can’t dive deep enough to reach the best resource and story areas, like the Deep Lilypads Cave or the Crystal Caves. The depth upgrade only takes 1 Plasteel Ingot and 2 Diamonds to craft, which you can find in the Koppa Mining Site around the same time you collect Magnetite for the Mercury 2.
Second, if you’re hauling 4 or more modules, you’ll still notice a small speed drop, even with the Mercury 2 installed. For short resource runs where you don’t need a sleeper module or aquarium, leave those extra modules docked at your base. You’ll get an extra 10% speed boost, and your battery will last even longer between charges.
Third, if you like to mod your game, you can find custom tweaks that increase the Mercury 2’s speed or reduce its power consumption even more, but don’t crank the speed above 50% higher than default. I made this mistake on my last modded playthrough, and I crashed straight into a Shadow Leviathan before I even saw it on my sonar, losing 3 hours of collected rare resources. It also makes it way too easy to clip through terrain and miss small collectibles like diamonds or rubies along the seabed.
At the end of the day, the Subnautica Below Zero Mercury 2 is one of the first upgrades you should chase on any new playthrough, and it makes every part of exploring the frozen ocean far less frustrating. You don’t need any late-game gear to find the blueprint, just a basic sea glide and a little patience to navigate the East Arctic. Once you have it installed, you’ll wonder how you ever played the game without dragging your slow, battery-hungry default Seatruck across the map.
