Specimen 13 resembles a young white woman with shaggy, grey hair. Before the chase, she is seen sitting on a floating crate, with her back to the player, wearing a towel around her waist. She reveals her true form during her death screen, where she morphs into a black-eyed elderly woman with long sharp teeth.
Specimen 13 lurks within the flooded rooms. She quietly sits on top of a floating crate. When the player gets too close, she will dive into the water where the player cannot see her and the chase will begin.
Specimen 13 deals 15 damage with a half a second cooldown.
Specimen 13 will only move when the player is standing in the water and can move through walls. She can only be detected through loud splashes she makes when moving. When the player stands on a crate, she won't move and will be unable to harm them. When the player goes back into the water, she will resume chase, although she will do so farther away than her last splash, preventing her from dealing unavoidable damage if she stopped moving too close to the player.
Once the player gets hit enough times, the screen will cut to Specimen 13's hair covered face, with bubbles appearing on screen, as if the specimen is submerging and drowning the player. The screen will then flash red a few times and show Specimen 13's true face before fading to black.
Sound made by Specimen 13 when it dives to chase the player:
Splashing sounds made when Specimen 13 moves in the water:
"Something In The Water", Specimen 13's chase theme:
Specimen 13's death screen sound:
- Specimen 13's behavior is a reference to Kaernk from the horror game Amnesia: The Dark Descent.
- Specimen 13's CAT-DOS entry may randomly show her face obscured by her hair or her true face.
- Specimen 13 can only be encountered once, along with Specimen 7.
- They are also the only two specimens absent in Endless Mode.
- Specimen 13 cannot reach the player while they are on top of one of the crates, despite the fact that she can be seen sitting on top of a crate before the chase.
- Specimen 13 may represent the Sirens found in Greek mythology.
Specimen 13's towel was replaced by what appears to be a fish's tail, and she now has a fully 3D model. She is wearing nothing on her top half. She now has a diving animation for diving into the water when the player gets close, but is still invisible when chasing the player.
The attack deals 45 damage, killing the player in 3 consecutive hits, but there is now a 3 second cooldown between each hit. She now moves faster than the player's sprinting speed while they're in the water but no longer goes through walls.
The number of rooms she can chase through in Story Mode has been reduced from around 30 to 10-19 rooms.She now appears in Endless Mode like she would appear in Story Mode within her rooms and will not re-chase, like Specimen 7. No other specimens can join the chase.