Book excerpt: Our PADI instructor hero extraordinaire John manages to endorse his reputation once more in this thrilling continuation of his diving escapades throughout Africa. Egypt didn't work out too well, and the Thistlegorm was far too busy anyway, so he sails south onboard Freya towards Tanzania accompanied as always by his pet dolphin Deapha. Lo and behold he comes across Mafia Island and the chance to dive with whale sharks and other large pelagic unicorns. And when you take a couple of punks diving one day, you just know its all gonna go tits up. And then there's the singeli hardcore festival in the excellently named Stone Town. What could possibly go wrong?