A shiver of sharks... diving the back of Jackson Reef in Tiran used to be one of the best or worst dives of the week.... we could only dive this site on particularly calm days as it was completely unsheltered to the North... (the direction of the prevailing wind). But on a calm day, or when a rare Southerly breeze was blowing, we could head back there in the Summer months in the hope of seeing Hammerhead sharks. I would literally pray that some showed up, because if they didn't, it was a bit of a bland, blue dive. The most I ever saw was four, but hubbie saw 19 once.