Thrill-seekers get ready: the longest zip-line in the world - 'The Jebel Jais Flight' - has officially opened today on top of the UAE's highest mountain, Jebel Jais in Ras Al Khaimah.Guinness World Records confirmed the length of the Jebel Jais zip-line at 2.8 kilometers – the equivalent to over 28 soccer fields – which beats the previous 2.2km world record in Puerto Rico by a full 600 meters of extra heart-pumping adrenaline.