The numbers strain comprehension. Amazonas is larger than Chile, Paraguay and Uruguay combined. Nearly all of it is rainforest. Roads are few. Most people and goods still move by boat along rivers that serve as highways, some stretching so wide that the far bank disappears into haze. From Belem at the Atlantic mouth to Manaus, the ferry trip runs roughly 96 hours upriver. Biologists estimate that the broader Amazon Region shelters about 2.5 million insect species, 2,000 species of fish, 950 species of birds and around 200 species of mammals. Roughly 200,000 Indigenous people live here across dozens of nations, including communities of Ticuna on the Peruvian border. The state is also home to Pico da Neblina, the highest mountain in Brazil.

At the end of the 19th century, the world wanted rubber for bicycle tires, telephone wires and the new automobiles, and the Amazon had it. Tappers bled latex from wild Hevea brasiliensis trees scattered through the forest, and the wealth flowed downstream to Manaus, Parintins, Tefe and Itacoatiara. The boom built opera houses and imported chandeliers up a river a thousand miles from the sea. It also killed or enslaved untold numbers of Indigenous seringueiros through disease and overwork. The bubble burst after rubber-tree seeds smuggled to Asia produced plantations that undercut Amazonian prices. The Belle Epoque buildings in Manaus and the old tiled sidewalks of the river towns are what remain of that brief, brutal prosperity.

Travelers come for the green. At Mamiraua Sustainable Development Reserve, one of the largest flooded forest reserves in the world at 1.1 million hectares, the water rises up to 80 continuous kilometers during the wet season, and dugout canoes glide between the tops of trees where white uacari monkeys feed. The reserve shelters more than 300 fish species and at least 45 mammal species. Near Novo Airao, the Anavilhanas archipelago scatters over 400 islands down the Rio Negro, one of the largest fluvial archipelagos on Earth. Jau National Park, a UNESCO World Heritage site, preserves vast stretches of untouched flora and fauna. From December to May, rain fills the waterfalls. In the drier months, white-sand beaches emerge along the Negro.

Amazonas eats what the forest and rivers provide. Tacaca, a soup of tucupi broth, dried shrimp, jambu leaves that tingle on the tongue, and gummy tapioca pearls, is sold from curbside stands in the afternoon. Tapioquinha, a chewy manioc pancake, arrives folded around buttery tucuma palm fruit and farmer cheese. Pamonha, green corn and coconut milk steamed in corn husks, turns up at markets alongside bolo de macaxeira, a dense translucent cake of grated manioc. The fruit is its own education: creamy white cupuacu with its sour-sweet pulp, purple-black acai beaten into a cold slurry, tart camu-camu, milky bacuri. Fish comes every way imaginable, from grilled tambaqui ribs to the massive pirarucu, one of the world's largest freshwater fish, dried and shredded like cod.

Manaus is the gateway, reached mainly by air through Eduardo Gomes International Airport, with domestic flights and connections from Miami, Orlando and several Latin American cities. A paved road links Manaus north to Boa Vista and on to Venezuela, but otherwise the way in and out is river or sky. Tabatinga International Airport serves the triple frontier with Peru and Colombia. The capital is generally safe, but rivers near the Colombian border pass through territory contested by traffickers and armed groups in conflict since the 1990s with police and each other. Ask locally before traveling into remote reaches. The heat is equatorial, humidity rarely relents, and the rains peak December through May.