You play your shot from a hazard which was buried in mud but soon realise it was not your ball. What happens?
Prior to 2008, you could play the wrong ball from a hazard and not be penalised, but since then the rule is the same for any other part of the course.
Rule 15-3 governs the situation arising from a golfer playing the wrong golf ball and the same rule applies when you are in a hazard too.
If you play the wrong ball from a hazard in strokeplay it is a two-stroke penalty provided you corrected your mistake before you tee off on the next hole. If you don’t, you’re disqualified. In matchplay, it is an automatic loss of hole.
You must identify your golf ball in a hazard like any other situation in accordance to the procedure in Rule 12-2. Lift the ball, it “must not be cleaned beyond the extent necessary for identification” and then replace the ball in the original conditions it was found in.
There is one exception to this rule which is as uncommon, as it is bizarre. You do not get penalised if you make a stroke at a moving ball in a water hazard. I’m assuming that this situation may arise when the ball is in a creek with the ball is moving around due to the water flow, making it difficult to identify and replace.