The Amazon rain forest is, of course, the world's largest remaining tropical rain forest, and Ecuador has a cherished two-percent share of it. Ecotours are proliferating here, as are cultural tours that let visitors experience something of the extraordinary indigenous lifestyle that is fast disappearing. Ecuador's Rio Napo, one of the mighty Amazon's primary tributaries, is home to some 200 distinct peoples who have been here for more than 10,000 years. Some ecotour operators let you meet members of the Siona, Secoya, Quichua, or Shuar groups and share some of their extraordinary knowledge of forest plants and wildlife. Barring total immersion—or volunteering with a nonprofit organization—you can visit the more accessible rain-forest areas of Cuyabeno Wildlife Reserve, Huaorani Protectorate, or Yasuni National Park even if you only have four or five days. Surtrek runs excellent small-scale tours to these areas and many others in the Amazon basin; you'll explore both on foot and via kayak, and spend the night in jungle lodges(www.surtrek.com).

These islands, which don't really need an introduction, were never part of the continent of South America, so their flora and fauna developed in isolation and subsequently gave Charles Darwin a unique window into the evolutionary process. Modern-day wildlife enthusiasts will find the islands (actually the peaks of underwater volcanoes, some of which are still active) just as fascinating; having never learned to fear humans, the copious animal species are amazingly approachable. The jumping-off point for touring the islands is the central Isla Santa Cruz, which contains the Charles Darwin Research Station and Puerto Ayora, with its population of 16,000. To the east is Isla San Cristóbal, which has the provincial capital of Puerto Baquerizo Moreno and a few visitor sites. The biggest island by far, formed out of the lava flow from six separate islands, is the 1,800-square-mile Isla Isabela, rife with iguanas, tortoises, orcas, penguins, and many other bird species. But it's the more southerly Isla Española that's best for the birds, harboring 10,000 breeding pairs of waved albatross as well as a giant colony of blue-footed boobies.

There are countless tour operators that can bring you around these islands and others in the archipelago, but Explorers' Corner (www.explorerscorner.com) and Ecoventura (www.ecoventura.com) are two of the best. Both offer small-scale luxury tours for fewer than 20 passengers. Explorers' Corner runs cruises on board a 34-foot sailing catamaran (with a small fleet of kayaks for exploring nooks and coves); Ecoventura has a trio of 83-foot motor yachts.

The coast of Ecuador varies enormously along its 1,400-mile length. The northernmost "Green Province" of the Esmeraldas, where the Spanish first landed in 1526, is part wild, lush tropical jungle and mangrove forest; part quiet shoreline dotted with fishing settlements; and part frenetic oceanfront resort. South of Esmeraldas, Manabí province is lined with resort cities like Puerto López, Montañita (a world-renowned surfing destination), and Salinas, which attract throngs of Quiteños and Guayaquileños in summer. More tranquil is Machalilla National Park, with the perfect Pacific beach of Los Frailes—a good whale-watching point. The central coast has mile upon mile of amazing white-sand beaches and fishing villages stretching all the way to unlovely Guayaquil. Ecuador's biggest city and main port, it's not a big draw, though there have been recent moves to upgrade its desirability. South of here, El Oro province continues all the way to Peru and is notable for its production of two major Ecuadoran exports, shrimp and bananas.

The stunning Andean highlands are getting easier to access, thanks to the array of newly opened haciendas in this region. More and more of the elite of the land are opening their ancestral piles to paying guests (although many are still working farms and offer small-scale lodging options like uniquely decorated rooms and home-cooked food). From these comfortable bases, you're free to explore a landscape more varied than it seems at first, with paramo (high-altitude grassland) and lush farmland alternating with cloud forest, mountain lakes, active and glaciated volcanoes, Incan ruins, thermal baths, and colonial towns. Here you'll see condors (if you're lucky—they're an endangered species), horses, llamas, and the people who tend them in their multicolored woven wraps and black trilby-like hats.

The capital, Quito, is partly colonial (in fact, its historic center has been a UNESCO World Heritage Site since 1978), but it's also part sprawling modern metropolis. North of Quito in the Imbabura province is the town of Otavalo, utterly unmissable on account of its huge daily market brimming with top-quality handmade goods (especially of the woven variety) as well as chickens, llamas, spices, potatoes, and exotic fruit. Imbabura's capital, Ibarra, with its colonial whitewashed buildings, cobblestone streets, and red-tiled roofs, is known as the White City. It's where to board the atmospheric, scenically stunning, but totally unreliable steam train to the coastal town of San Lorenzo. Near here is the center of the world—literally. The Mitad del Mundo, the monument that marks the equator, is nondescript, but it's still kind of cool to know you're straddling the earth (so to speak). Other major must-sees (or must-hikes) are the Avenue of the Volcanoes—the jagged southern Andean region stretching from Quito to Cuenca—and Cotopaxi National Park, home to the Mount Fuji of Ecuador, the perfect snow-capped cone of Cotopaxi. At well over 19,000 feet high, it's the world's second-highest active volcano, and it's breathtaking.