Basic Fins are the earliest swim speed upgrade in Subnautica 2, and they come together from two crafted materials you can gather within sight of the Lifepod. The full chain runs through Lucifer Rotsacs, Fibrous Pulp, and a quick stop at the Fabricator.
Basic Fins recipe breakdown
The fins themselves are a Personal item at the Fabricator, but both ingredients are processed materials. You will not find Rubber or Fiber lying on the seafloor. Both come from plants near the Lifepod that you break down with the Survival Multitool, then convert under the Resources tab.
| Item | Fabricator tab | Inputs |
|---|---|---|
| Basic Fins | Personal | 2 Rubber + 2 Fiber |
| Rubber | Resources (Basic Materials) | 2 Lucifer Rotsac |
| Fiber | Resources (Basic Materials) | 2 Fibrous Pulp |
Once crafted, the fins slot into their dedicated equipment slot automatically and provide a small movement speed boost while swimming.
Prerequisite: Survival Multitool
You need the Survival Multitool before you can collect Fibrous Pulp. It costs 3 Titanium, which spawns as gunmetal-gray geometric chunks across the sandy floor directly beneath the Lifepod. Larger Titanium clusters break into two or three pieces with multiple interactions.
Craft the Multitool at the Lifepod Fabricator under the Personal tab. Lucifer Rotsacs can be collected by hand, but the plants that drop Fibrous Pulp require the tool to shred.
Where to find Lucifer Rotsac
Lucifer Rotsac is the glowing orange (sometimes red-orange) bulb growing at the center of a Cradle Shootroot. The host plant has sea-green leaves tipped with orange and a starfish-shaped bud holding the rotsac in place. Both glow strongly in the dark, which makes them trivial to spot at night.
The densest early cluster sits roughly 100 meters north of the Lifepod along the shallow ocean floor. Individual Cradle Shootroots also appear scattered across the surrounding shallows and on derelict structures in the area. Each bulb yields one Lucifer Rotsac, and you collect them by interacting with the bud directly. No tool required.
For Basic Fins specifically, you need 4 Lucifer Rotsac (enough for 2 Rubber).
Where to find Fibrous Pulp
Fibrous Pulp drops when you chop certain plants with the Survival Multitool. The Cradle Shootroots that hold the Lucifer Rotsacs are one of the best early sources, so you can stack both errands on the same trip. Whip Gorgon, which looks like thick red tentacle-grass tufts in grassier patches around the Lifepod, also yields pulp.
Feather Kelp inside the cave roughly 100 meters northwest of the Lifepod is another reliable source if you want to farm in bulk. Macaron Sponge works as well once you encounter it.
For Basic Fins, you need 4 Fibrous Pulp (enough for 2 Fiber).
Crafting at the Fabricator
Step 1: Return to the Lifepod with at least 4 Lucifer Rotsac and 4 Fibrous Pulp in your inventory. Interact with the Fabricator on the left side of the pod.
Step 2: Open the Resources tab and select Basic Materials. Craft Rubber twice (consuming 4 Lucifer Rotsac total), then craft Fiber twice (consuming 4 Fibrous Pulp total).
Step 3: Switch to the Personal tab and select Basic Fins. With 2 Rubber and 2 Fiber in your inventory, the recipe will be available. Craft them, and they will auto-equip to the fins slot on your character profile.
You will know it worked when the fins icon appears in your equipment slot, and your base swim speed visibly increases the next time you move underwater.
Why this recipe is worth doing first
Silver, the gating material for the Standard Air Tank, is hard to find in the opening hours and usually requires pushing into shallow caves several hundred meters north of the Lifepod. Basic Fins do not need any metal beyond the Titanium you already spent on the Multitool, which makes them the cheapest meaningful mobility upgrade available right after escaping the Cicada wreckage.
Rubber also carries forward. The same 2-Lucifer-Rotsac recipe feeds into the Air Bladder and the Standard Air Tank later, so any rotsacs you over-harvest now will not go to waste. Fibrous Pulp similarly doubles as a food ingredient once you have unlocked the Digestion Adaptation from the Angel Comb northeast of the Lifepod.