If you want a no nonsense experience on the reef, this is the tour to take. Reef Sprinters get's you out to a private and isolated section of Low Isles in about 15 mins on a 500HP boat.
Because this section of the reef is restricted to them, there is a maximum of 14 people which keeps the fish close due to not being scared off. The water is also a lot less murky with less people kicking sand up from the bottom.
Marina rented a camera from this same shop and took some fabulous photos. She swam with the turtle for about 15-20 minutes and the photos are absolutlely amazing! http://www.reefsprinter.com.au/