Three hours north east of Bangkok, the traffic has ground to a halt. Surrounded by the evergreen forests and grasslands of Khao Yai National Park, the cars soon find themselves backtracking from an unexpected menace – wild elephants on the road. A few minutes away though, there is no stopping the momentum of Thailand’s biggest musical event, the Big Mountain Music Festival. Now in its fifth year, and held on Khao Yai’s Bonanza Racetrack in picturesque nature, it has grown into the largest festival in South East Asia, attracting 130,000 people over two days.