Check these out Flight of the gibbon experience www.treetopasia.com I reckon the biggest drop was betwen 40 - 50 meters, so quite high, no railings on any of the platforms, but we all had safety harnesses on and the guides were very good as far as safety goes, as you wern't going to walk away from a fall. Most of the time you could not see the platform you were going to land on, which made for some interesting touch-downs when travelling backwards. I also have a picture of a viper, which I nearly stepped on walking up the waterfall we went to, the photo is blurred so I've not attached it. Ziplinning was fantastic fun, and the big vertical drop at the end was wicked.