They have a whole complex of them here in Dalat. I think there are five separate courses altogether starting from beginner up to what they call the black course. But you don't just zipline from tree to tree. You need to traverse somewhat of an obstacle course each time you finish a line to get to the next tree to get to the next zipline. The zip lining is very easy. No issue there. The physical exertion comes in when crossing over to the next zipline on their obstacle courses. I paid $18 to do the whole course today. Takes about 2 and 1/2 hours to do the whole thing. I will admit I was a little wore out after I was finished. I shot some video and I'll convert it to YouTube and post it here next week. Was a lot of fun.