4. Skyline Akaka Falls, USA

Here at Skyline Eco Adventures in Hawaii, you have seven choices of zip-lines but there are two highlights. One is a cable that takes you 246+ feet over the gorgeous Kolekole waterfall, ensconced in the tropical jungle. The other noteworthy ride is the final wire that takes you across an almost 450-foot wide canyon complete with a raging waterfall right under you.