Tsitsikamma Zipline, South Africa

Travelers repeatedly cross South Africa's scenic Kruis River gorge on the Tsitsikamma Zipline, which runs through a nature reserve, features eight ziplines, and passes close to several waterfalls. And you'll actually have time to appreciate the sights, since you can adjust your speed on these well-engineered lines. Go fast, but also remember to go slow. The views are worth lingering over.