The Cavitation Muffler is a Tadpole upgrade module in Subnautica 2 that reduces the noise your submarine makes, lowering the chance that hostile creatures notice you. The blueprint isn't earned through scanning fragments. Instead, you pick up a single Recipe Data Card from a piece of wreckage in deep water near the Blackbox - Zip 2 trench.
What you need before going
The trench is deep, narrow, and runs alongside a red kill barrier that instantly kills you if you cross it. You don't need a Tadpole with a depth module to grab this specific blueprint, but having one makes the trip far safer. On foot, the dive is survivable with the right loadout.
| Recommended gear | Purpose |
|---|---|
| High Capacity Air Tank | Extends underwater breathing time for the deep descent |
| Air Bladders (3–4) | Emergency oxygen refills mid-dive |
| Seaglide or Wakemaker | Faster travel down and back up the trench |
| Tadpole with Depth Module | Optional but heavily recommended for safety and speed |
How to reach the Cavitation Muffler data card
Step 1: Set the Blackbox - Zip 2 beacon as your destination. From the surface, it sits roughly 2,055m out, near the Alien Ruins marker. Swim to the area on the surface to conserve oxygen.
Step 2: Once you're above the trench, dive straight down toward the Blackbox - Zip 2 marker. You'll quickly run into a tall, red, grid-like barrier in the water. Stay parallel to it and never cross. Touching the other side results in instant death.
Step 3: Descend along the rocky cliff face next to the barrier. Use an Air Bladder when oxygen gets low to surface yourself briefly, then continue down the narrow trench until you reach the seabed.
Step 4: On the ocean floor, you'll see a Thermal Plant structure and surrounding wreckage adjacent to the red barrier. Look for the wreckage with a small data box on it. The interaction prompt reads "Take Cavitation Muffler recipe data card."
Step 5: Interact with the data box. Two notifications appear on screen: "MODIFICATION STATION | NEW BLUEPRINT SYNTHESIZED" and "CAVITATION MUFFLER UNLOCKED!" The blueprint is now permanently added to your Modification Station.
How the unlock works
Recipe Data Cards in Subnautica 2 are one-pickup unlocks. The card looks like a horizontal white box with a small hologram of a computer chip floating above it. Picking it up immediately adds the recipe to your Modification Station without needing multiple scans or fragment collection.
You'll know it worked when the "CAVITATION MUFFLER UNLOCKED!" message appears on screen and the module shows up under your Tadpole upgrade options at any Modification Station.
What the Cavitation Muffler does
Once crafted at a Modification Station and slotted into your Tadpole, the Cavitation Muffler dampens the engine's acoustic signature. Hostile fauna that rely on sound to detect you are less likely to give chase, which makes deep exploration and trips through predator-heavy zones considerably less dangerous.
Avoiding a wipe on the way back
The trip back up is where most players die. Oxygen runs out fast at the bottom of the trench, and hostile creatures patrol the cliff faces near the wreckage above the seabed. Keep at least two Air Bladders in reserve for the ascent, and consider scanning the nearby Thermal Plant, Metal Farm fragments, Tadpole Hull Chassis, and Hydroelectric Turbine fragments while you're already down there to make the dive worthwhile.
With the blueprint secured, slot the Cavitation Muffler into your Tadpole at any Modification Station, and the upgrade is active immediately. It's one of the more useful early-to-mid game modules for anyone planning to venture into deeper biomes where aggressive wildlife is the main threat.