Anavilhanas Ecological Station

The amazonian manatee, endemic to this region, faces a high rate of extinction in the wild. Anavilhanas is also home to other threatened species, including the giant arapaima fish, black caiman, and two species of river dolphin. While this area is protected by government decree, hunting and pollution from ships traveling the Rio Negro put the area at risk.

All manatees are not created equal. Take the Amazonian manatee, for example. It's the only freshwater manatee, and it's smaller than the other two species, on average only 3m (9 ft.) long and 450kg (992 lb.; granted, that's still big). A timid creature, it minds its own business in the backwaters of Amazon basin rivers. Since it only has molar teeth, its diet is limited to soft aquatic plants. Mothers only have one calf at a time, which they nurse for up to 2 years. So when the natives hunt them for meat and leather, invade their waterways with motorboats, and destroy their specialized habitat—well, it's hard for the manatees to hold their own.

The Amazonian manatee is just one species being studied and protected at the Anavilhanas Ecological Station, a Brazilian government nature reserve just northwest of Manaus (access is through the lodge of the same name). Set in the Rio Negro, a major Amazon tributary, it encompasses some 400 islands and hundreds of lakes, rivers, swamps, and sandbanks, the world's largest archipelago in a river. Since the reserve was created in 1981, it has relocated nearly all the inhabitants of the archipelago. And still, residents of Novo Airão and Manaus visit the islands to fish, hunt, and cut wood; Manaus building companies take sand and stones from the riverside, though rangers are monitoring this activity closely. Ships cruising the Rio Negro add pollution to the equation. And, of course, politics snarl up everything, with many locals increasingly resistant to international "interference" by conservation groups.

Though the islands of Anavilhanas are covered with forests, these are special forests, adapted to the fact that the islands are largely submerged during the high-water period, April to June. Notice, for example, the tree's aerial roots as you navigate around the islands in small boats—those come in handy when a tree is flooded for months at a time You'll see a lot of palm-trees, orchids, lichens, and on some islands, straggly shrublands; a lot of trees have curved, thin trunks and leathery leaves that can store water for the dry months. Animals are driven to higher ground, too, until the waters recede, revealing beaches and deeper channels. September and October may be your best months if you want to see wildlife.

Given the changing conditions of the river, the landscape is constantly shape-shifting, with islands relocating and channels altering their courses. A local guide, however, can help you keep your bearings, as well as identify the flora and fauna, most of which are unique to this one-of-a-kind environment. As you maneuver around its labyrinth of channels, lakes, and island, keep an eye peeled for those elusive manatees—or at least the playful river dolphins.