Just about to go windsurfing and we noticed a black thing in the water. What looked like through the binos, a massive fin standing straight up probably 3 foot high, one or two other fins visible and a long long body, just drifting very slowly, almost not moving first one way then really slowly back again. The water was not that deep, it was at Snapper Point Reef. We first thought it was a seal but really the fin was massive. There wasnt much wind, so we sailed out towards it to check it out but couldnt see it at the time, course I fell off and hardly enough wind to get back on the board, felt a little creepy so we went back in. It was still there and hung around for an hour or so. Any ideas?