In golf, a water hazard is any body of water: a lake, the sea, a canal, a pond, a creek, etc. Water hazards may be introduced by the course designer (as a canal or pond), or may be a natural part of the surroundings.

When your ball ends up in a water hazard, you are penalized. You may play the ball from the same location as before, or from the last piece of land it flew over on its way to take a swim. (This is one of the few exceptions to the rule that you must play it where it lies.)