What happens if I hit a wrong ball that's moving in water?

No penalty — the stroke is cancelled. If you swing at a wrong ball that's moving in water (in a penalty area or temporary water), the stroke doesn't count and no penalty applies. You simply play your actual ball from its original spot or take the appropriate relief. This is one of the Rules' rare "free pass" exceptions: a wrong-ball swing that normally costs two strokes in stroke play or loss of hole in match play is completely erased when the wrong ball happens to be moving in water.

Why this exception exists

The Rules recognise that identifying a ball moving in water is often impossible — water distorts visibility, balls look identical when submerged or splashing, and the current can carry a ball away before you reach it. Penalising a player for an honest mistake in these conditions would be unfair, so Rule 6.3c(1) Exception 2 removes the penalty entirely. The stroke is treated as if it never happened.

The exception in plain English

Rule 6.3c normally gives you the general penalty (two strokes in stroke play, loss of hole in match play) for playing a wrong ball. But there's a specific carve-out: if that wrong ball is moving in water — either in a penalty area or in temporary water — you walk away clean. The stroke is cancelled, no penalty strokes added, and you just correct the mistake by playing your actual ball or taking whatever relief applies.

What you do next

Since the stroke doesn't count, you're back to square one with your real ball. If you know where your ball is, go play it from there. If it's lost in the penalty area or temporary water, you take relief under the normal options — stroke-and-distance, back-on-the-line, or lateral relief for a penalty area; nearest point of complete relief for temporary water. No extra penalty for the wrong-ball swing.

Match play nuance

In match play, the general penalty for a wrong ball is loss of hole. The moving-in-water exception still applies — you don't lose the hole for that swing. But if you and your opponent accidentally play each other's balls during the hole, the first one to make a stroke at the wrong ball loses the hole (unless the moving-in-water exception saves them).

Exceptions that change the answer

• The wrong ball is moving in water inside a penalty area → No penalty. The stroke does not count. Play the correct ball from its original spot or take penalty-area relief.
• The wrong ball is moving in temporary water → No penalty. The stroke does not count. Play the correct ball from its original spot or take free relief for temporary water.

Frequently asked questions

Does it matter if I knew it was the wrong ball?

No. The exception applies regardless of whether you realized it was a wrong ball. The stroke is cancelled either way.

What if the ball was moving in water but not in a penalty area or temporary water?

Then the exception doesn't apply. Normal wrong-ball penalty: two strokes in stroke play, loss of hole in match play.

Do I have to find my original ball first?

If you know where it is, play it from there. If it's lost in the penalty area or temporary water, you can take relief without finding it — just use the normal relief options for that situation.

What if I hit a moving ball in water that turns out to be mine?

That's not a wrong ball — it's your ball. Rule 10.1d covers playing a moving ball: no penalty if it's moving in water in a penalty area or temporary water, but you must not make a stroke at a ball moving in water elsewhere.

Can I just drop a new ball instead of finding the original?

Only if you're taking relief under a Rule that allows substitution (like penalty-area relief or temporary-water relief). If you're playing the ball as it lies, you must use the original ball.