Australia
The Edge
The Edge is a cube that slides out from the Eureka Skydeck 88 observation deck of Melbourne's Eureka Tower. When the cube is fully extended, the walls and floor turn transparent—and as if that weren't scary enough, speakers blare the sound of shattering glass. The Edge opened last spring; up to 12 people can spend five minutes suspended over the city. Only one in three Skydeck visitors is willing to brave the Edge, but of the 30 marriage proposals that have been tendered inside, there hasn't been a single no.
011-61/3-9693-8888, eurekaskydeck.com.au, $25 for Skydeck and the Edge. — Susan Crandell
Panama
Canopy Crane Tour
More than 70 percent of all rainforest species hang out high in the canopy, but it's not like you're going to climb a tree yourself. Tour operator Cox & Kings USA, however, is using the Smithsonian Tropical Research Institute's crane to bring you face-to-face with the fauna in Panama's Metropolitan Natural Park. The crane raises four guests and a naturalist guide 112 feet up through the treetops—and as much as 160 feet out in any direction. "When I first did the tour, we spotted a napping sloth and zoomed in for a closer look," says Susan Lee, who does marketing for Cox & Kings. "The naturalist imitated the call of an eagle, one of the sloth's main predators. The sloth looked at us, decided there was no danger, and went right back to sleep." Other commonly seen animals include green iguanas, toucans, and red-naped tamarins. The best time to take the 45-minute tour is between 6:30 a.m. and 9 a.m., when the wildlife is most active.
800/999-1758, coxandkingsusa.com, $110 per person (based on four people), no children under 12, reservations are required. — Beth Collins
Tennessee
Zorb Smoky Mountains
Where some people see a hillside, others see a thrill ride. The popular New Zealand activity of Zorbing—in which you tumble down a slope while inside a plastic bubble—has arrived in the U.S., at Pigeon Forge, Tenn. Before you start, there's a two-page waiver to sign, five different courses to pick from, and two Zorb options: You can sit strapped into a seat or flip head over heels in a ball filled with water. ("It's like white-water rafting without the rocks," says CEO Craig Horrocks.) The 12-foot spheres reach speeds of up to 35 mph; the view is a blur of trees, sky, and your limbs, punctuated by the occasional scream of "Awesome!"
865/428-2422, , from $37 per ride. — Liz Ozaist
Arizona
Grand Canyon Skywalk
More than a few visitors to the Grand Canyon Skywalk at Grand Canyon West white-knuckle their way around the 70-foot-long, U-shaped glass structure, never letting go of the railing. Others jump up and down for the Skywalk's photographers, unbowed by the view of the jagged canyon about a mile below. The $30 million attraction opened last spring after years of collaboration between a Las Vegas businessman and the local Hualapai tribe, which owns much of the canyon's western rim. The surrounding area remains a work in progress, as a theater and a restaurant are under construction—so is the 14 miles of as yet unpaved road that leads to the entrance, making for a rather bone-rattling approach.
, $60 includes admission to the reservation and the Grand Canyon Skywalk, cameras not allowed. Bus tours depart daily from Las Vegas, about two hours west (702/878-9378, , from $159). — Henry Cabot Beck
Florida
SeaWorld's Aquatica
The star attraction of SeaWorld Orlando's new water park, Aquatica, is Dolphin Plunge—a pair of 300-foot-long transparent tube slides that weave through an actual marine-mammal habitat. The black-and-white Commerson's dolphins who frolic in the lagoon seem to enjoy the action, too. "When I was zipping through the tunnel, the dolphins were following alongside me," reports operations director Bryan Nadeau. "For a moment, I felt like I was in their world." The water park also has an eight-lane racing slide that whips you in and out of tunnels and around a 360-degree loop.
888/800-5447, , $39, $33 for kids ages 3 to 9. — Jessica Henderson
Maine
Penobscot Narrows Bridge and Observatory
The first Penobscot bridge, completed in 1931, was crumbling into the Penobscot River, so everyone agreed it was time for a new-and-improved bridge—if not on much else. "At first, the city wanted something that looked like the old structure," says Bruce Van Note, deputy commissioner for Maine's Department of Transportation. But area residents rejected every proposal, eventually coming up with a one-word idea of their own as inspiration: granite. "To lifelong Mainers, granite is rugged and timeless, and it matches the state's rocky coast," says Van Note. Made primarily of local Freshwater Pearl granite, the new Penobscot Narrows Bridge and Observatory is one of only three cable-stayed bridges in the world to also have an observation tower (the others are in Slovakia and Thailand). No matter which direction you look from the glass-enclosed deck, the views are postcard-worthy.
207/469-7719, , $5, tower open May 1-Oct. 31. — Sarah Mahoney
Singapore
Singapore Flyer
When it opened March 1, the Singapore Flyer captured the title of the world's tallest observation wheel from China's 525-foot Star of Nanchang. The 541-foot Flyer has 28 gondolas; each one holds up to 28 passengers and rotates 360 degrees over Marina Bay. Watch your step while boarding: The Flyer never stops moving. "That surprises a lot of people," says general manager David Beevers. "But once the doors close, it's quite serene inside the glass capsule as it ascends over the bay." Halfway through the 30-minute ride, you're up high enough to see Malaysia and Indonesia.
011-65/6333-3311, , $21, timed tickets can be purchased online in advance. — David LaHuta