The great annual water festival, goes by many names in Southeast Asia, in Thailand it’s known as Songkran. It ushers in the start of rainy season in April, a time when after five excruciatingly dry months the sky finally opens and water pours on to the bone dry land. It’s celebrated nationwide with mass water fights and traditional Buddhist rituals. The Northern Thai city of Chiang Mai is widely known for where the water really gets flowing.