Message from the ocean floor: tread carefully FROM the top deck of Spoilsport, a five-star live-aboard dive cruiser, the outer edge of the Great Barrier Reef 50km east of Cooktown shimmers like a ribbon of white on an ocean of deep blue. Below the surface, Steve's Bommie, a circular sub-sea tower crusted with coral, rises from the depths to a vibrant plateau 3m below the gentle waves.