Zipline. It just sounds fast, especially zipping over a hundred feet above the majestic, rugged beauty of Juneau's mountains, glaciers and waterways. Juneau's two tree-top zipline tours give a true bird's-eye view of the Tongass rainforest. On these eco-adventures or "canopy tours," expert guides zip with you from platform to platform amid the towering trees.

Both tours allow you to traverse sections of double-cabled ziplines from 150 to 800 feet long that link a series of platforms. Alaska Canopy Adventures begins with a scenic boat ride across the Gastineau Channel to the site of the old Treadwell Mine on Douglas Island. You'll learn the mine's lore on your way to the outfitter hut, where you'll be suited up and then head up on a 6x6 off-road vehicle to the first of nine lines.

A scenic drive across the Douglas Island bridge to Eaglecrest Ski Area will take you to Alaska Zipline Adventures, which boasts seven zip lines and an aerial suspension bridge over running mountain streams. AZA also offers trips combining zipping with a Mendenhall Glacier trip or a Jeep/Hike adventure.

Zipline riders control their speed, but can reach up to 30 miles an hour. A leisurely glide or an adrenaline-charged zip - you choose! To make the most of your Juneau zipline tour, you should be comfortable with heights, able to walk short distances on groomed trails, and up and down stairs. Don't worry about the rain, as both tours provide rain gear. Just remember to keep your eyes open!