From Pathfinder Dark Archive (Remastered), which isn't enabled.

False Floor

HAZARD 3

Stealth +13 (trained; or 0 if the illusory floor is dispelled)

Description The floor in this chamber is an illusion, which conceals a 40-foot drop to the true floor below. Additionally, the area beneath the floor is magically silenced-no sound is audible within nor does sound leave this space.

Disable Succeeding on a DC 21 Perception check against the Stealth DC of 21 (including the check to find the trap) disbelieves the illusory floor, or Dispel Magic (2nd rank; counteract DC 18) to dispel the illusory floor; dispel magic (2nd rank; counteract DC 20) to dispel the magical silence

Drop

Trigger A creature walks onto the illusory floor

Effect The triggering creature falls through the illusory floor and takes falling damage (typically 20 bludgeoning damage). That creature can use the Grab an Edge reaction to avoid falling. The DC to Climb the walls or Grab an Edge is 20.

Reset The trap resets after 1 round.

Pathfinder Dark Archive (Remastered)ORC