I've had a similar experience about 6 months ago in the island of koh Samet. We decided to spend the week end there with some friends and as we were enjoying a cold beer under a beautiful night sky, a friend who was swimming came rushing towards us screaming to come and check the water. We did. It turned out to be one of the best experience of my life. The water lit up as we swam and it reminded me of a scene in the "life of pi" movie. A truly mind blowing moment.