Accursed Pool CR 3
The lingering effects of ancient curses or harmful energy leaching from a submerged cursed magical item can turn a simple pool of water into a dangerous magical hazard.
An accursed pool lures passersby into its depths with a silent image (DC 16 Will save to disbelieve) of glittering treasure at the bottom of its 10-foot depth. Any creature that reaches the treasure triggers the curse. A creature within the pool must make a DC 16 Will save or be affected by the curse, which warps its perception of the pool. The water seems to thicken into viscous goo, while the pool appears to distort to a depth of 40 feet. Swim checks in the pool suffer a –10 penalty and are at half normal speed as a result of these effects, and spellcasting within the pool requires a concentration check with a DC of 15 + the level of the spell being cast. An accursed pool radiates strong magic, and is destroyed by dispel magic or remove curse (caster level check DC 15).
Pathfinder RPG GameMastery Guide, © 2010, Paizo Publishing, LLC; Authors: Cam Banks, Wolfgang Baur, Jason Bulmahn, Jim Butler, Eric Cagle, Graeme Davis, Adam Daigle, Joshua J. Frost, James Jacobs, Kenneth Hite, Steven Kenson, Robin Laws, Tito Leati, Rob McCreary, Hal Maclean, Colin McComb, Jason Nelson, David Noonan, Richard Pett, Rich Redman, Sean K Reynolds, F. Wesley Schneider, Amber Scott, Doug Seacat, Mike Selinker, Lisa Stevens, James L. Sutter, Russ Taylor, Penny Williams, Skip Williams, Teeuwynn Woodruff.