I'll be spending a few days in Cairns in March 2010. I want to do some snorkelling and see the Great Barrier Reef. To be honest I'm pretty scared which probably sounds stupid but I'll be 62, on my own (female) and have never snorkelled before. I really want to do it but I know I'll feel very uncomfortable on a huge boat surrounded by loads of confident younger people. Is there a smallish company who would be patient with someone like me?