I did this at the Maetaman elephant camp in Chiang Mai, Thailand. There were two men on the raft guiding us down the river, they were fun trying to overtake and race other rafts and pushing them off course. It was really nice and tranquil and you could hear various birds and animals in the jungle either side.
http://i1112.photobucket.com/albums/k481/LauraRenee87/My%20bucketlist%20pictures/HPIM0723.jpg
They also let us have a go at guiding the raft ourselves. I have to say it looks easier than it is. Not only are you trying to not lose your balance, it is also made harder as the river drags the stick away so you have to hold on to it tight!
http://i1112.photobucket.com/albums/k481/LauraRenee87/My%20bucketlist%20pictures/HPIM0731.jpg
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