While Ecuador's slice of Amazonian pie is comparatively slim, the Oriente is still one of the most abundantly complex and fragile areas in the world.

Freshwater dolphins cruise flooded forests; blue giant morphos flutter through shafts of light; and tamarinds observe the unwitting visitor. Consider its mega-biodiversity -- 50 percent of the country's mammals, 5 percent of Earth's plant species and more than 600 bird species reside here. So do many indigenous groups negotiating life between modern and ancient ways. Such otherworldly territory usually marks the domain of intrepid wilderness devotees, yet Ecuador's Amazon basin is the most accessible of any in South America, reached in two hours from urban centers via spiraling highland roads.

Despite an ease of access and diverse attractions, the Ecuadorian jungle remains a puzzle to navigate. Visitors to Quito find hundreds of agencies shuffling packages from dozens of outfitters, some of whom change name or disappear midseason.

If you want to explore the jungle, consider the kind of trip you're looking for. Jungle lodges usually charge the plumpest rates, which earn you a comfortable base for short excursions, a steady supply of buffet dinners and dry socks. While animal sightings can't be guaranteed, most operators can advise you on the probability of seeing certain animals, and their Web sites often feature lists of sighted wildlife. Observation towers offer panoramic views of the canopy, best for bird- and monkey-viewing. Naturalist guides and multiple outings per day further improve your chances of spotting that elusive anaconda or rufous potoo.

Hire a guide

Cheaper tours require flexibility, a strong stomach and a sense of adventure. While few local guides speak English, they can be extremely knowledgeable.

Do your homework with these outfitters, and you will be justly rewarded. Check on group size, as battalions of tourists tend to spook the critters. Watch for those that cut corners with unsound practices such as dumping trash or hunting for your dinner. The biggest drag of the bargain operations is that they often go into easy-access jungle around populated areas greatly depleted of animals. When arranging your trip, inquire how long the tour provider has been around and research travelers' Web sites such as Lonely Planet's Thorn Tree for complaints. The South American Explorers site (www.saexplorers.org) offers members helpful trip reports written by fellow travelers.

Fragile ecology

A visitor can't enter the jungle unaware of its fragility. Ecuador has the highest rate of deforestation of any Amazonian country. Antiquated oil-extraction technology and insufficient cleanups of past spills mean contamination continues to be a reality in areas where indigenous groups are dependent on clean water and healthy wildlife for survival.

As the indigenous struggle for self-determination continues, more and more are turning to ecotourism as an alternative to oil. Trips with a focus on indigenous cultures can be arranged through both high-end and community tourism. While village areas are often depleted of wildlife, these visits do provide an unparalleled understanding of life in the jungle, income for the community and the opportunity for memorable cultural exchanges.

Few operations offer sustenance behind the claim of ecological sustainability. Look for those whose hard work has paid off with prestigious awards and widespread respect. Community-run programs at least keep funds within local populations. At Napo Wildlife Center, cooperatively run with the Quechua Anangu community, all residents must give consent for oil exploitation. Sani Lodge is another community-owned and community-run initiative. At Yachana, local youths get a high school education on-site, paid for by funds raised from visitor fees.

Hang out in the jungle

Jungle lodges with a conscience:

Napo Wildlife Center (011-593-2-289-7316; www.napowildlifecenter.com; packages for three or four nights, $595/$795) is the only lodge within the boundaries of Parque Nacional Yasuni. Trips are guided by local Anangans trained as park rangers and bilingual naturalists. Birders will crow over the parrot clay licks and 36-meter steel tower. The environmentally sustainable sewage system is the only one of its kind on the Napo.

Sani Lodge (011-593-9-434-1728; www.sanilodge.com; packages per person for three or seven nights, $285/$665) reinvests tourism profits into the local Quechua community with scholarships and a community store to ease local hunting. Monkeys, sloths and black caiman are regularly spotted, and the 30-meter tower will help you gander at the 550 listed bird species. The lodge is located four hours from Coca.

Yachana Lodge (011-593-2-252-3777; www.yachana.com; packages for three or four nights, $345/$460) offers birding, hikes and community visits with strong interaction on the local level. From Coca, it is a 11/2-hour motorized canoe ride to the lodge. Highlights include a traditional healing ceremony and hiking along 20 kilometers of trails. The Shuar and Quechua indigenous guides speak English.

For active travelers: Coca-based Emerald Forest Expeditions (011-593-6-288-2309; emeraldforestexpeditions.com; $50 per day) offers camping tours to Laguna Panacocha, a cloud and dry-land forest with dolphins, macaws and toucans. "Survivor" wannabes can embark on a 10-day trekking and canoe trip to Iquitos, Peru, via the Napo River.

Cultural tourism

Papangu (011-593-3-883-875; guiding $40 per day) is an indigenous-run agency in Puyo offering community tourism in the Quechua and Shuar communities.

?Sacharicsina (011-593-6-288-6839; sacharicsinatour@yahoo.com; guiding $25-$40 per day) in Tena offers river and community tours through a warm local Quechua family.

Carolyn McCarthy has contributed to the Lonely Planet guides "Ecuador & the Galapagos" and "South America on a Shoestring." "Travels With Lonely Planet" is coordinated by Global Travel editor Don George. You can e-mail him at don.george@lonelyplanet.com. For more travel information, visit LonelyPlanet.com.