Depends, was it on when it got wet? salt or fresh water? Did you immediately pull the battery? Those answers will give you your chance of recovery.
The best thing you can do (at this point) is make sure the battery is out. If you dunked it in salt water, FLUSH IT WITH FRESH WATER!. If you dunked it in fresh water, then just give it lots of time to dry. If you can pack it in a container with dry rice and seal it for about a week would be great to sucking the last of the moisture out. After that, put in a fresh battery and hope for the best.