Keeper potholes are low spots in canyons where water often collects. Keepers can be one of the most dangerous aspects of canyoneering if you're not prepared for them. They take specialized skills and gear to escape. Luckily there are a huge number of canyons without keeper potholes, so do those first. Once you're comfortable with the other aspects of canyoneering, then it MAY be time to do canyons with potholes.