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It’s a Trap: the Water Bath

It’s a Trap: the Water Bath

water lilliesWater is essential to life. It nourishes plants, it slakes thirst…

But it also smothers with its icy embrace and boils flesh from bones. Never underestimate water.

One of the first water themed traps you’ll come across is the classic water-filled room.

Water-Filled Room Trap (CR 4)

Type mechanical; Search DC 17; Disable Device DC 23
Trigger location; Reset automatic
Effect room filled with water, 10 ft. by 10 ft.; multiple targets (all targets in room); never miss; onset delay (5 rounds)
Market Price 11,200 gp…

This is a lethal trap, or to be more precise, this is a campaign-ending death trap. Basically, it is a save or die effect: if you fail to spot the trap, it kills you in 5 rounds plus the number of rounds you manage to hold your breath. The trap just feels incomplete: for instance, can the doors be breached in 5 rounds?

“Maybe we should have gone the other way…”

Tiny droplets of water fall from the ceiling of the corridor, creating small pools of water on the floor.

  • You determine that a large volume of water is located above the corridor, possibly an underground river or lake, with a DC 13 Knowledge (dungeoneering) check
  • You determine that the ceiling of the corridor is in excellent condition with a DC 15 Knowledge (architecture and engineering) check


The rune symbol on the map shows where the trigger is located; the map assumes that the intruders arrive from the right side of the map. If the trap is triggered, creatures occupying the red colored squares can make a DC 15 Reflex save to evade the trapdoor that will swing into place, sealing off the corridor. Anyone succeeding on the save ends up outside the trap’s area of effect while failing the save deals 4d6 bludgeoning damage and forces the target outside the trap’s area of effect.

As the trapdoors swing into place, the water held above the corridor pours down into the sealed off corridor through the grates once hidden by the trapdoors. Everyone who is still in the area of effect takes 2d6 nonlethal damage and is pushed towards the center of the corridor. The water quickly fills up the corridor, and at the end of the round, the corridor is completely submerged. The area above the corridor now only holds a couple of inches of water, but two iron grates prevent access to that area: it takes a DC 23 Strength check to break each grate, and each grate has hardness 10 and 15 hp. The trapdoors are strong wooden doors and have hardness 5 and 20 hp. The doors cannot be forced open with a Strength check; the sheer volume of water prevents that. Slashing and bludgeoning weapons are less effective underwater (consult the rules for underwater combat).

Breaching one of the trapdoors violently drains the corridor. Everyone who is still in the water-filled corridor, or in front of the breached door, is dragged away for 30 ft. and suffers 6d6 damage, a DC 20 Reflex save halves this damage. If the doors are not breached the trap resets itself automatically after 4 hours. The water is drained away, the trapdoors are lifted, and a create water effect fills up the area above the corridor.

Water-Filled Corridor Trap (CR 5)

Type mechanical; Search DC 24; Disable Device DC 24
Trigger proximity; Reset automatic
Effect two swinging trapdoors (4d6; DC 15 Reflex avoids); multiple targets (all targets within 5 ft. adjacent)
Effect downpour of water (2d6 nonlethal damage; pushes targets to center of hall); multiple targets (all targets between two trapdoors)
Effect water surge through breached door (6d6; DC 20 Reflex for half damage; pushes all targets 30 ft.); multiple targets (all targets either in water-filled corridor or outside and adjacent to breached door)
Market Price 27,700 gp


You can always hold your breath for a number of rounds equal to twice your Constitution. After this period of time, you must make a DC 10 Constitution check every round in order to continue holding your breath. Each round, the DC increases by 1. (See also Swim skill description.) If you fail your Constitution check, you begin to drown. In the first round, you fall unconscious (0 hp). In the following round, you drop to -1 hp and are dying. In the third round, you drowns.


Welcome to It’s a Trap! Week. To start the occasion, David Schwartz blurred the line yesterday between trap and monster with the plague cart, and today, Maurice de Mare is back with his regular series of traps and a certain watery demise for the hapless.

With Thanksgiving right around the corner for many KQ.com readers, this week should give you just what you need to catch that turkey (or its more docile cousin, the tofurky). Water trap? How about a brine trap? That bird’s gonna be juicy.

(This post is Product Identity.)


Let the lying in wait for your prey begin!

3 thoughts on “It’s a Trap: the Water Bath”

  1. These are some great traps, really really deadly. I’m planning on taking my PCs into a partially submerged temple later in my current campaign, this will be a good trap to use as they will be forewarned about water hazards and thus prepared to not die in this scenario.

  2. i could augment this trap to suit a campaign im designing and change the water into lava…:)

    yes im an evil GM….lol

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