From Pathfinder #210: Whispers in the Dirt, which isn't enabled.

Swamp Stealth

FEAT 5

Activity 1 action

Prerequisites expert in Stealth

Requirements You are in a swamp environment near an environmental feature that would allow you to Take Cover.

In swamplands, you are particularly skilled at quickly hiding behind bits of underbrush or foliage, or moving quietly through murky water. You Take Cover and then use that cover to Hide.

Pathfinder #210: Whispers in the DirtORC