Rain forests are the rock stars of Earth's ecosystems, generating nearly a third of the planet's oxygen turnover and hosting mind-boggling biodiversity. From soaring vines and canopies to majestic fauna sheltered in a huge canopy of green, they practically demand an audience.

Amazon

Brazil, South America
Among rain forests, the Amazon reigns supreme: It comprises some 1.4 billion acres, predominantly in Brazil but including parts of eight other nations. A fifth of the world's birds and a tenth of all species on the planet live in this steamy realm, where a single square mile can pack upwards of 75,000 different types of trees. From over a hundred types of frogs to piranhas, electric eels, pink dolphins and clangorous scarlet macaws, Amazonia is the zenith of Earth's biodiversity. While deforestation continues, sustainable tourism can foster conservation efforts. Tour operators such as National Geographic Expeditions and Abercrombie & Kent offer Amazon River cruises.

Cathedral Grove

MacMillan Provincial Park, Canada
Cathedral Grove is living proof that a beautiful rain forest isn't necessarily difficult to find. Part of Vancouver Island's MacMillan Provincial Park, it is essentially a stand of giant Douglass fir trees, some of which are, astoundingly, more than 800 years old. You'll find ancient Western red cedar trees in this old-growth coastal forest, too. There are excellent nature trails on either side of the highway that wends through the park--you'll find most of the fir trees on the south side. You might spot black bears, woodpeckers and cougars, too.

Lamington National Park

Australia
If you're looking for the elusive Coxen's Fig Parrot or eastern bristlebird, you'll probably have a better chance of spotting them in this rain forest park than from wherever you're sitting now. Lamington forms part of Queensland's Scenic Rim and is only about 18 miles from the Pacific. Its dramatic, deep green plateaus and cliffs are remnants of an ancient volcano. From waterfalls to wallabies, this park has it all, along with miles of walking tracks. There's also a Rain forest Canopy Walk, a network of rope-and-plank suspension bridges 50 feet above the forest floor, in the Green Mountains section. You can overnight at O'Reilly's Rain forest Guesthouse, or take a day trip by bus from Brisbane (75 miles to the north) with Allstate Scenic Tours.

Cockscomb Basin Wildlife Sanctuary

Belize
The most famous resident of this 155-square-mile tropical moist broadleaf forest, on the eastern slopes of the Maya Mountains, is also the most elusive: the jaguar. In fact, Cockscomb is pretty much ground zero for the world's foremost jungle cat, but because they're so stealthy, you're more likely to see (or hear) howler monkeys and some of the 290 bird species that call the basin home, too. There's also an abundance of red-eyed tree frogs, tapirs, ocelots, armadillos and pumas. More than 100 inches of annual rainfall feed the forest's waterways, making rafting trips a great way to explore. Rafters leave from the Swasey River or South Stann creek, zipping past the base of lofty limestone cliffs.

Hana Rain Forest

Maui, Hawaii
If you can survive the road to Hana along the island of Maui's rugged eastern coast (just make sure those windshield wipers are in good working order), you'll be in for an endless supply of natural green splendor. That includes, but is not limited to, stunning cliffs and verdant ravines, waterfalls, black sand beaches, the island's last lava flows, deep rain forest on the northeastern flanks of the Haleakala volcano, and the Pools of Ohe'o (Seven Sacred Pools). Hana's rain forest is easy to experience independently, but a local tour outfitter can give you a more up-close and personal look at this tropical beauty spot.

Koke'e State Park

Kauai, Hawaii
Cliffside views and hiking trails figure prominently in the popularity of this Hawaiian rain forest, where some 70 inches of rain fall annually (for the most part between October and May). There are panoramic views of the Kalalau Valley from an elevation of 4,000 feet, and plentiful opportunities to hike in native rainforest and along the rim of dramatic Waimea Canyon. The 2.5-mile Kukui Trail drops 2,000 feet into the canyon (which is part of another state park). Wildland picnicking, tent camping and lodging are all easy options here.

Yakushima Island

Kagoshima, Japan
On the three-hour drive around this lush island where some of the mountains reach heights approaching 6,000 feet, you'll come across Yakazuru monkeys, Yakushika deer, and maybe even a Tanuki raccoon dog. The cloud forests are home to Yakusugi cedar trees, whose roots even extend from the leaves and stalks, forming strange shapes. The Jomonsugi cedar, growing at an elevation of some 4,000 feet, is at least 2,000 years old. At Hirauchi Kaichu Onsen you can soak in a thermal spring next to the ocean, and at Sango-no-hama, or Coral Shore, collect star-shaped sand. With so much to see, you might consider a three-day tour departing from Tokyo.

Monteverde Cloud Forest Reserve

Costa Rica
Golden toads, luscious orchids and brilliant quetzals, oh my! There's a whole lot of biodiversity going on at Costa Rica's premier nature preserve, and one that helped put ecotourism in this compact Central American country on the map. Some 118 inches of rain fall on this vast forest annually, and that helps confer upon Monteverde the distinction of having more orchids than any other place in the world. If you don't spot a quetzal (a brilliantly colored, highly elusive bird), you might get buzzed by hummingbirds, of which there are more than 30 varieties here. There are nine main nature trails for visitors and several lodges for overnight stays.

Erawan National Park

Thailand
Gibbons, rhesus monkeys, macaques, cobras and elephants are some of the animal kingdom heavy hitters in residence at this rainforest park in Thailand's Kanchanaburi Province. In the natural features department, the star attraction is the seven-tiered Erawan Falls, named for a three-headed white elephant in Hindu mythology. You can swim in the pools formed by the falls, and explore the forest on any number of nature trails. There are also limestone caves, such as Phrathat Cave. About seven miles north of the park's main visitor's center, it features enormous stalactites and stalagmites--and more than a few bats.

Tarkine

Tasmania, Australia
Located in the northwest corner of Tasmania, the Tarkine is the remnant of an ancient supercontinent and is home to Australia's biggest swath of temperate rainforest. It's also home to that famously feisty little marsupial, the Tasmanian Devil. But some 60 rare species are also found here, including the giant freshwater lobster and Tasmanian wedge-tailed eagle. This primordial paradise also boasts enormous sand dunes, pristine rivers and expansive beaches.