If you're an adrenaline junkie, zip lining is probably on the top of your activity list. Perhaps you've tried it before and have loved the feeling of flying through the sky with just you, a harness and a rope. But if you're looking for a truly amazing buzz, you may want to check out the list below for some of the most incredible, belly-turning zip lines from around the world. These adventures, from news.discovery.com, are sure to leave you breathless as you fly at speeds up to 100 mph over rivers and mountains, past volcanoes and even the Great Wall of China. So you better get out your passport and pack your bags – these zip lines are waiting for you. 
It's believed the zip line in Hoonah, Alaska – called the ZipRider, is one of the largest in the world. It runs more than a mile, with a 1,300 foot vertical drop over a 90-second ride. A total of six riders go together on parallel lines and race to the bottom. With this zip line you are guaranteed a good view. Riders fly over Hoonah's tree-covered mountains and the ocean below. 
This zip line, called Mokai Gravity Canyon's Flying Fox, turns riders over onto their stomachs and flies them parallel to the ground. It runs 3,600 ft with riders hitting 100 mph. You will literally feel like you are flying through the Rangitikei Canyon as you soar over the riverbed below. The line then runs under a bridge and up towards a cliff face. 
The zip line at Costa Rica's Arenal Volcano Park is a ride like no other. The nearly two-mile ride over a series of zip lines will take you through the jungle, over Arenal Lake and past Arenal Volcano, which last erupted in 1984 and is still active, although it is closely monitored. The Sky Trek is part of the larger program that includes a Sky Walk along bridges in the jungle and a ride in an open-air gondola that takes you into the treetops so you can zip back down. 
This zip line is said to be the longest one in the world that goes over water. It runs 2,600 feet over a cove and has beautiful views of the blue water and distant mountains. There is a 500-foot vertical drop with speeds reaching between 40 and 50 mph. 
This zip line is open year round and offers incredible views for each season. A winter zip line will take you through a snow covered forest and over frozen creeks. A summer ride will take you through breathtaking running creeks. The lines run from 200 to 1,000 feet, including a freestyle line that lets you hang upside down.
With locations in Chiang Mai, Bangkok and Pattaya, you can zip your way through the country with these tours. Instead of one long ride, the tour here offers zip lining between treetop platforms and rappelling descents. They also offer river rafting, mountain biking and rock climbing. Perhaps the best part about these tours is the fact that the money you pay to experience the jungles of Thailand will go towards protecting them, since a profit of the tours goes to protecting the endangered gibbon and the rain forests. 
Many zip lines offer incredible sights, but few offer views of one of the seven wonders of the modern world. The zip line in Gubeikou Twon of Miyun County offers just that. To get to the starting point you have to hike up the Great Wall of China. To get back down you can zip line over Mandarin Duck Lake, which gives you a unique view of the Great Wall and of the mountains surrounding it.
Who said you have to travel to an exotic place to get your adrenaline rush? Rockbridge, Ohio offers Hocking Hills Canopy Tours, where you can take part in the SuperZip. It runs a quarter mile and offers speeds up to 50 mph. You will find yourself soaring from a canopy tower down into the forest, over a cliff and the Hocking River. You can also take part in a three-hour canopy tour, which is a series of 10 shorter zip lines where you will learn all about local history. 
The zip line aboard the Royal Caribbean's Allure of the Seas is a must for any zip line lover. The ride lasts a little under 10 seconds but you get to fly nine flights above the boardwalk where your fellow passengers are walking. 
The Zip 2000 in Sun City, South Africa claims to be the longest zip line in the world with a 6,500-foot ride reaching around 93 mph. Riders here hang two-by-two from the cable with a fin between their legs for extra speed. It also offers a gorgeous view of the South African grasslands 1,000 feet below.
