The 2015 DEEP Indonesia contest is now entering its last few days for entries. Together with the now-closed Our World Underwater, it will distribute over $90,000 worth of prizes to winners in 6 categories. In all of them, digital manipulation is allowed, however the competition is definitely a photographic one, and excessive use of post capture tools is discouraged. Your entries must be with the organisers by 27 February.
Full rules and entry procedures are on the UnderwaterCompetition.com website.