Today’s Wonder of the Day was inspired by Sara from Prince Rupert. Sara Wonders, “Why were ziplines invented?” Thanks for WONDERing with us, Sara!

Have you ever wished you were a bird? Well, maybe not just any bird…after all, it might not be much fun to be a chicken or a turkey. But what about an eagle? Do you think it would be fun to soar through the skies?

If you could fly, where would you go? Would you follow the paths of the great rivers to the oceans? Or would you explore the tops of mountains or the depths of the Grand Canyon? If you could get a bird's eye view of anything or anywhere in the world, what would you want to see?

Humans have used their desire to fly to inspire them to create all sorts of inventions, from airplanes to helicopters. These machines can certainly fly you through the air, but they don't give you the same feeling as if you were a bird.

Would you believe that there is an invention out there that can make you feel somewhat like a bird? It's true! What are we talking about? Zip lines, of course!

Zip lines are simply cables that connect two points. One end is higher than the other, providing a natural slope that allows a person to travel along the cable. A pulley system helps to reduce friction, so that the rider can accelerate as he flies through the air.

No one can say for sure when zip lines were first invented. However, historians believe that people in mountainous areas, such as the Himalayas and the Alps, began using zip lines early on in their cultures as a means of transporting supplies over dangerous terrain. Mountain climbers have also used them for many years as a way to cross dangerous mountain gaps.

More recently, zip lines have become more popular because of their use by wildlife biologists. These scientists discovered that using zip lines was one of the best ways to travel through and study the forest canopy.

In some areas of the world, zip line tours — sometimes called canopy tours — are a form of eco-friendly tourism. For example, in Costa Rica, zip line tours are a popular way of exploring the rainforests.

Although you can use zip lines just about anywhere — and you'll find them all over the world — they're not always called zip lines. In Australia, for example, they're called flying foxes. In South Africa, they're foefie (pronounced “foofy") slides.

So just how fast can you zip through the air on a zip line? Very fast! Some zip lines will propel you through the air at speeds of up to 100 miles per hour!

Speed isn't the only thing that's thrilling about zip lines, though. Part of the thrill is also seeing the world from a different viewpoint. Zip lines have been set up in some very neat places to give riders a glimpse of the world they wouldn't otherwise get.

For example, you can zip over deep valleys, rivers, and even crocodile pens! There are even some school children in Colombia who use a zip line to get from their isolated village to school every day. Now how cool would that be?

Wonder What's Next?

Tomorrow’s Wonder of the Day will take you about 100 miles off the coast of Florida!