Having grown up with National Geographic, I had always dreamed of seeing the Amazon rainforest and its wildlife. But my Brazilian wife, Maria, a carioca (a native of Rio de Janeiro), had a better idea: the Pantanal, the world’s largest freshwater wetland.

Sprawling across a Colorado-sized stretch of outback Brazil, Bolivia and Paraguay, the Pantanal is a hydrological wonder: Every October, rains in the surrounding highlands overwhelm its shallow basin; every April, this epic flood recedes, leaving rich sediment and a shifting mosaic of open savanna and gallery forest, scrub grassland and wooded copses, water holes and meandering rivers.

According to Valmir Ortega, director of Conservation International’s Pantanal program, this extreme, varied habitat supports one of South America’s richest ecosystems: 3,500 species of plants; 450-plus species of birds; 325 types of freshwater fish; and more than 120 different mammals, including such endangered species as jaguar, maned wolf and pampas deer. It is the Pantanal, not the Amazon, which holds the greatest visible concentrations of New World fauna.

In the wet season, when the water can rise 10 feet, animals cluster on high ground. In the dry season, they never stray too far from sweet-water baías or brackish salinas. The bipolar weather also discourages development. Only a few hundred thousand pantaneiro cowboys live in this flood plain, where for centuries the only commercial option has been seasonal ranching.

“The Pantanal’s a unique region on the planet,” Ortega told me, citing its combination of biodiversity, hydrography and limited human occupation which gives it “an exceptional scenic beauty.”

Like most Brazilians, my wife first learned of this swamp from El Pantanal, a groundbreaking telenovela, or soap opera. Equal parts The Thorn Birds and Wild Kingdom, the racy backwoods saga about a jaguar that shape-shifted into a beautiful woman and her country-boy lover gave the mystical wetland a prime-time close-up for nine months.

After El Pantanal’s 1990 debut, curious travelers began to arrive, usually flying from São Paulo to the few gateway cities of this near-trackless wilderness. Inns sprouted along the Transpantaneira, a ramshackle, 90-mile causeway south of Cuiaba that is the only access into the northern section of the swamp. On the teeming rivers outside Corumba, near the Bolivian border, sport fishermen occupied floating “botels’’ and cast for salmon-like dourado and 200-pound jau catfish.

On the southern edge of the swamp, an area served by the cattle town of Aquidauana, ranches such as Fazenda Barranco Alto, Hotel Barra Mansa and Fazenda Santa Sophia also began lassoing small groups of adventure-minded eco-tourists. These spreads present an ideal setting for a South American-style safari: Instead of the Amazon’s dense triple-canopy jungle, the Pantanal’s mosaic of open landscape promises fabulous game viewing.

At these fazendas, all-inclusive programs typically include day-trip expeditions on horseback as well as by boat and canoe. Their menus feature heaps of free-range beef and savory feijão com arroz, followed by afternoon siestas in a hammock, then spectacular sunsets chased with caipirinhas — “lethal” cocktails of crushed fruit, ice, sugar and 80-proof cachaça liquor.

Although I had hired a driver and 4-wheel-drive vehicle in Campo Grande for our expedition into the interior, I discovered that almost no one — not even a local — attempts surface travel into this ferocious, car-devouring wilderness. Not unlike rural Alaska, an expedition into the southern Pantanal is best undertaken in a chartered bush plane — a fact I realized after an ancient, 2.5-ton Dodge truck from a fazenda winched my city-slicker wheelman and his bogged-down Land Cruiser from the anaconda-infested mire. But the Pantanal is worth the whole boot-sucking ordeal.

Our first morning broke with the chatter of a half-dozen cobalt-blue hyacinth macaws, the world’s largest parrot. Beyond the ranch’s horse paddock, a herd of capybaras (pig-sized aquatic rodents) emerged from the tree line and settled serenely into a wallow. Down by the tannin-stained Rio Negro, several dozen spectacled caiman basked in the rising sun.

As our boat pilot maneuvered an outboard-powered skiff along the river, we witnessed magnificent birds of a hundred different feathers, including brilliant toco toucans and funereal jabiru storks, ostrich-like rheas and black skimmers carving the water for fish with their shear-shaped bills. As we motored past sandy banks pocked with the dens of giant and neotropical river otters, more capybara materialized from the riverside forest while the caiman count soon exceeded three figures. That wasn’t all: Camera traps had also photographed a puma and three different jaguars on the property.

While these fazendas have survived for more than a century in relative harmony with the Pantanal, the region is threatened by upstream discharge of agricultural pollutants as well as deforestation from charcoal-makers supplying metal foundries in Corumba.

Compared to the Amazon, however, the resilient Pantanal remains healthy; more than 80 percent of the massive wetland is still in excellent natural condition. Steeled by the annual cycle of wet-season floods and dry-season fires, the marsh demands belligerent biology. In a sink-or-swim place where 30-foot snakes eat 120-pound rodents, there’s no room for wallflowers.

Out here, the appeal isn’t found in stunning scenery, though the suave sunsets are stunning. The attraction builds subtly: a morning on horseback; an evening game drive; a quiet boat ride leading to a claw-scarred “jaguar tree’’ and, further upriver, the corpse of a male giant river otter. We chase the vultures and caiman attracted by the stench and land to inspect the body to determine the cause of death. Nothing obvious, my guide says, maybe snakebite. It happens.

Death, and life, continue here in a daily struggle. The Pantanal isn’t a petting zoo. It’s certainly not a Bonanza-style ranch. It’s what it always was and, with any luck, will remain: a hard, beautiful place.

The day of my departure, the sky cast a leaden pall — a thermal inversion from the burning season on surrounding fazendas. We took a pair of canoes and headed upstream, following a pair of curious giant otters for several hundred yards, then landed near a bend in the river. The caiman reluctantly ceded the beach, but hung 10 yards downstream in the current while I took a wary dip. “Don’t worry too much about piranha,” the pilot cheerily advised. “They prefer still water.’’

Fishing with a bamboo pole and a scrap of beef, my son immediately pulled a thrashing piranha from a nearby pool. Time to get out of the water — I’ve seen too many feeding frenzies on the Discovery Channel.

The low clouds opened and the first heavy rains in months pelted the parched earth. Our return road trip promised to be another gripping, muddy adventure. Back at the fazenda, a ranch hand tore off a piece of cardboard and drew a crude map for me. At each cattle gate he indicated one encouraging direction: Segue. Continue. “What day is your flight back to the States?’’ my guide asked. When I answered, he just smiled. “Then you have three days to get to Aquidauana.’’

Info To Go

From São Paulo (GRU) or Brasilia (BSB) it’s a 90-minute domestic flight to Campo Grande (CGR). Several family-owned ranches along the Rio Negro offer prime game viewing and bird watching, including Fazenda Barranco Alto, Barra Mansa Lodge and Fazenda Santa Sophia. They are best reached by bush plane from Campo Grande or Aquidauana, 80 miles to the west. Visit www.turismo.ms.gov.br.