It's a classic Underwater Onion.
YOU HAVE TO READ THIS FIRST BEFORE LOOKING AT PICTURE.
Family on vacation in Australia for a week and a half when husband, wife and their 15 year old son decided to go scuba diving. The husband is in the navy and has had some scuba experience. His son wanted a picture of his mom and dad in all their gear so he got the under water camera ready to go. When it came to taking the picture the dad realized that the son looked like he was panicking as he took it and gave the 'OK' hand sign to see if he was all right.
The son took the picture and swam to the surface and back to the boat as quick as he could so the mom and dad followed to see if he was OK. When they got back to him he was scrambling onto the boat and absolutely panicking. When the parents asked why, he said 'there was a shark behind you.' The dad thought he was joking but the skipper of the boat said it was true but they wouldn't believe him. As soon as they got back to the hotel they loaded the picture onto the laptop and this is what they saw.