Back in January this year we were lucky enough to get an opportunity to swim with dolphins in Cocos (Keeling) Islands. Some of the images can be seen at http://www.uwimages.com.au/portfolio/cocos-keeling-islands
What was really special and unique about this experience is that we had two different species of dolphins swimming and playing together. This doesn't happen in many parts of the world.
I had a GoPro mounted on the top of my underwater housing and my wife Sarah-Jo Lobwein had a Nikon AW1 point and shoot camera. Here is a quick video from our experience.
Hope you enjoy it!