The Waterslug is a creature in Subnautica 2, one of the first alien fauna species confirmed for the game. It was revealed through a creative alternate reality game (ARG) that used an in-game Time Capsule mechanic from a prior franchise title to deliver hidden clues to players.
The Time Capsule ARG
Starting in July 2024, developers at Unknown Worlds began planting specially crafted Time Capsules into the in-game messaging system of a prior franchise title. Time Capsules are an endgame feature where players leave messages, screenshots, and items for other players to discover in their own playthroughs. The developer-planted capsules were designed to look like normal player entries but contained images of a creature that did not exist in any prior franchise game.
Identifying the Capsules
Community members identified the capsules as developer-planted through several distinguishing features:
Each capsule carried the hashtag #PEEPERSRULE in its database description
The screenshots showed close-up images of a creature not present in any prior franchise game
Each capsule name followed the format "TC" followed by a string of numbers
The images were macro-photography-style close-ups showing only fragments of the creature's body, deliberately cropped so no full-body view was visible
By July 29, 2024, gaming outlets had covered the story, and three Time Capsules had been discovered containing Waterslug images.
The Hexadecimal Puzzle
A community member identified as _Erod_ made the key breakthrough. The numerical strings appended to the "TC" prefix in each capsule's name were not random: when converted from hexadecimal to ASCII text, they spelled out the word WATERSLUG. This hexadecimal encoding served as both the creature's name reveal and a puzzle for the community to solve collaboratively.
Developer Scott MacDonald (forum username "Obraxis") acknowledged the capsules on the Steam forums with deliberately coy responses, replying to a screenshot post with a shrug emoji and telling Discord users "Huh. Funny that." when fans shared the images. He subsequently confirmed the name "Waterslug" directly after the community decoded the hexadecimal message. Community moderators cryptically stated that "there may or may not be others to find," suggesting additional capsules were still hidden.
Physical Appearance
The three Time Capsule images each showed close-up shots of different anatomical sections of the Waterslug, intentionally cropped to prevent a full-body reconstruction. The screenshots revealed:
Feature | Source | Details |
|---|---|---|
Fin structures | Time Capsule screenshots | Multiple fin-like appendages visible in the close-up images. |
Long eyes | In-capsule flavor text | A caption reads: "I found this thing on the ground... I have no idea what I'm looking at, but I think it's friendly? It has long eyes!" |
Translucent body | In-capsule flavor text | Another caption reads: "I have no idea what this thing is but it seems to be pretty clear and filled with something. Can I drink it?" This suggests at least parts of the Waterslug are transparent or semi-transparent. |
Body sections | Images showed distinct body sections and partial head anatomy in addition to the fins. |
Community member _Erod_ built a fan 3D model of the Waterslug based on the three partial screenshots, attempting to reconstruct the full creature from the fragments. The model was shared on the official forums as a speculative interpretation.
Post-ARG Appearances
On January 24, 2025, Unknown Worlds posted a birthday celebration screenshot that featured a Waterslug, marking the first time the creature appeared in an official developer image outside of the hidden Time Capsule context. This confirmed the Waterslug's continued presence in the game's development and provided a clearer look at the creature than the cropped ARG images had allowed.
Behavioral Hints
The in-capsule caption text provides the only behavioral hint about the Waterslug. The message "I think it's friendly?" (written as in-universe flavor text by the developers as part of the ARG) suggests the Waterslug may be a passive or non-aggressive creature. However, this is flavor text rather than a direct developer statement about game mechanics, so the creature's actual aggression level, threat classification, and defensive abilities remain unconfirmed.
Significance of the ARG
The Waterslug ARG was notable for several reasons. It arrived before Subnautica 2's official announcement, making it one of the earliest concrete confirmations that a sequel was in development. It demonstrated Unknown Worlds' willingness to use their existing games as a marketing platform. And it repurposed an in-game asynchronous-connection feature (Time Capsules) for an entirely new purpose.
The ARG also showed the community's collaborative puzzle-solving ability. The hexadecimal encoding, the #PEEPERSRULE hashtag, and the developer's deliberate non-answers created a layered mystery that required collective effort across community forums and chat channels to unravel.
The Water Slug in the Shipped Build
The teaser questions this page was built around were answered when the game shipped. The Water Slug is a live creature in the Early Access build, not a silhouette: it is a small collectible organism documented in the Graveyard sub-area of the Coral Gardens, and it is harvestable rather than merely observable.
It is a carryable object. A Water Slug can be picked up and held in the player's inventory, and Buddy System Hotfix 1 corrected its breath markers so they show only while the slug is a physical object in the world rather than while it is stowed.
Players collect them in bulk. The Buddy System update shipped visual-effect optimisations specifically for the Graveyard and its Water Slugs, with the patch notes describing them as being for players who collect hundreds of them.
The related Flash Slug is a Fabricator ingredient: combined with Salt it yields Isotonic Water, one of the better hydration items in the build. See Flash Slug for that recipe.
Nothing in the patch notes treats it as a hazard. It is handled throughout as a collectible resource rather than a threat, which is the reading the community took from the original capsule caption.
What is still undocumented, as of September 2026, is whether the Water Slug yields a specific adaptation when sampled with the Biosampler, and its place in the wider food chain of Proteus.