South East Asia has a lot of festivals, most of them involving water and lights it seems. The Yee Peng Festival in Chiang Mai is so far the most impressive one that I have come across. As far as I could tell it involved lighting lanterns and trying not to get them tangled on powerlines, in trees or stuck in the river with the end goal of sending them into space.
Any concerns of littering or burning the poor sods downwind was soon forgotten when you saw the absolute magnitude of people, decorations and most importantly the lanterns that were being sent skyward. No wonder they had to close the nearby airport for the night so people could be free to let the lanterns run free.
Definitely a sight to see, and I was very glad that my trip coincided with this festival, even if it meant spending another week in the north of Thailand rather than on the beaches. But travelling is sometimes about making sacrifices.