The creatures of the Pantanal

We pulled up in front of the sprawling farmhouse of Refugio da IIha and our host, Leonardo Copetti, strode out to greet us. "Welcome, come in," he said. "I can show you to your room, or maybe first you'd like to meet the anaconda that has been living under our stairs for the past few days?"

I recognize that these words would not signify the start of a dream holiday for all travellers. And if you are not fond of 2.5-metre constrictors who curl up in the shade of the steps, or crocodiles who mosey up on to the dock or piranhas in your swimming hole, then this is not the trip for you.

But the Refugio is a refuge in every sense, not just for the rare species that shelter in its jungle and its waterways, but for world-weary humans, too. Our visit was so magical that I managed to quell (most of) my anxiety as I watched my children crane their heads under the steps for a better look at the snake that Copetti affectionately called Ana, and risk their lives a dozen other ways.

The Refugio is located on the southern edge of the Pantanal – an exotic-sounding name that, in Portuguese, actually just means swampy. It is the world's largest tropical wetland and one of the most bio-diverse places on the planet. It's a river delta, where hundreds of tributaries venture down from the heart of South America headed for the coast, and 80 per cent of it submerges during the rainy season.

The Pantanal is home to hundreds of bird species – some exceedingly rare, such as the mesmerizing hyacinth macaws, and the jabiru stork, which loped awkwardly past as we canoed one day, stretching out its eight-foot wingspan. There are reptiles galore. The waters are so clear in the wet season that you can see dozens of types of brightly coloured fish flit past.

But it was the mammals who really charmed us: ancient-looking armadillos, furry giant anteaters with sweeping feathery tails and capybaras who minced out of the foliage on their tippy-hooves. Some lucky visitors spot shy, sleek jaguars; we didn't. But we … we saw the otters.

It was the otters that lured me into this trip: In addition to the standard furry fellow you think of, the Pantanal is home to Pteronura brasiliensis, the giant river otter. It grows to nearly two metres as an adult: yes, otters, taller than you are. They are voracious predators; the 40-member clan that lives on the Salobra River, which surrounds the Refugio, consume one ton of fish each month. They are fierce, fighting off crocodiles and jaguars that hunt their young. And they are endangered, hunted to near extinction.

I've wanted to see the otters since I first learned of them when we moved to Brazil four years ago, and I took my family on the long trip into the Pantanal (two flights and a four-hour drive from our home in Rio) on an otter pilgrimage. On our first day, Copetti took us on a long evening boat cruise, and we saw a shoreline marked with distinctive otter claw marks: They had been there recently, but they eluded us. When we got home to the lodge after dark, staff told us that, in fact, giant otters had been out front noisily scarfing fish while we were downstream.

Up just after sunrise the next day (courtesy of the bird life), we went up the river – way up the river. More signs of otters. No actual otters. I began to despair. Then while my son, Darragh, was swimming in the river that afternoon, a furry, whiskered head popped up not far from his; the otter looked at him inquiringly for a moment, then disappeared. Darragh was elated. I haunted the shoreline: no otters sightings for me.

But on our third morning, we took canoes down the river – this experience alone was worth travelling across Brazil. We weaved under the vines and around the sharp bends, surrounded by banks of water plants blooming pink and white, eyed warily by capybaras and herons and the occasional caiman, sunning itself on the bank. And then, up ahead: one! Then two! Then three otter heads, popping up and disappearing and popping up again to study us.

One had a fat fish in his mouth. By the time we paddled up close, a couple of them had disappeared into a tangle of foliage. We couldn't see them – but could we hear them. They tore and crunched through those fish, so loud that it drowned out the giggles that Darragh and I could not stifle. That, Copetti told me, is what it sounds like when giant otters eat. It was like a junior-high cafeteria.

The Refugio offers English-speaking guides, a rarity in Brazil, who are full of facts, from how long it takes an anaconda to poop out a meal (and be hungry again, the key detail) to how much an anteater eats (35,000 ants a day).

I loved the otter lore best: The clan on the river has been extensively studied by teams of naturalists hosted at the farm, who have been tracking just how hard it is for a young otter pair to break away and start a new group. An established otter clan raises its offspring communally, allowing some adults to go fishing while others mind the pups. But a new pair have to leave the pups alone in order to eat – and other otters, from the established clan, are the chief menace, determined not to let anyone else horn in on their territory. If a young breeding pair do not manage successfully to raise a litter after a couple of years, they split up and go back to their respective families – the same family that has been relentlessly hunting down their young. Otters, apparently, aren't ones to dwell.

Copetti's parents bought the 4,000 hectares in the 1970s, intending it as a rice farm; rice did not grow well here, and so eventually they began to raise cattle. But so many visitors came and raved that eventually they turned to the hospitality business. Copetti and his mother run operations, his brother sometimes joins to guide and the whole family is often on hand for the delicious meals in the screened room overlooking the river. They are charming and warm and eager to have everyone love the Pantanal as much as they do. The big hearty farm meals were the best food I've had in Brazil, and there was icy craft beer in the fridge.

The family has left more than two-thirds of its farm a protected reserve, and plays down the environmental impact of the cattle ranching. The Pantanal has been protected, to some degree, from the impact of Brazil's rapidly expanding industrial agriculture by the fact that it is too swampy to grow much; it cannot be plowed into soy farms. But about three-quarters of the entire wetland is cattle ranches, and while traditionally this was free-range, low-density ranching, there are increasing amounts of deforestation and pastureland burning carried out to accommodate the estimated three million bovines that live there. Brazil's government has done little to safeguard the region; at the Refugio, they carry out their own patrols to watch for illegal fishing on the protected river. The otter clan cannot afford the competition.

We had one more visit from the otters, not close enough to see their creepy webbed-and-clawed paws, but enough to sense their extraordinary strength and speed as they pushed up through the strong river current. Even our fleeting encounters felt like a gift. And the crocodiles, as if to compensate, were ubiquitous: Coming back by boat one night after dark, Copetti cut the motor to show us a pair of glowing red eyes in the tangle of brush on the shoreline. And then another pair gleamed, and another: It was a mother Paraguayan caiman with newly hatched young. A whole lot of young. We counted more than 50 pairs of red eyes in the dark. It was marvellous, and terrifying.

The next day, my children were fishing for piranha off the dock when a couple of hungry caiman gathered to catch the fish that got away. Then one particularly opportunistic reptile decided there were plumper pickings to be had on land, and slipped out of the water and up the riverbank. He had slithered to within a couple of metres of the children when Copetti suggested they quietly and calmly turn around and have a look at who was behind them. They were, of course, delighted.

You have a choice to make: when to visit the Pantanal. Come in November through April, for the wet season, when the area is a vast network of waterways, of shimmering reflections and towering cloud formations. You can snorkel the river surrounded by fish, but you may see fewer birds and mammals. Daytime temperatures hit 45 C. Or come in the dry season, May to October, when it is cool (read: 28 C) and the landscape is less lush and more scrubby, but it is easier to see animals in the dry grass and breeding birds congregate near the shrinking ponds.

Copetti told me, on our last morning, that we must return at the height of the floods, because that is the Refugio's "most magical moment." We will return, I think – because even from the dry season, we're hooked on the magic of the Pantanal.

If you go

Campo Grande is a 90-minute connecting flight from Sao Paulo, with flights by three reliable Brazilian airlines: GOL, Azul and TAM. Car rental is straightforward in Brazil with an international licence; Unidas is the cheapest firm, but Movida is easier to deal with. You will pay about $400 for a small car for a week.

Pack generous quantities of bug repellent (you can carry liquids of all sizes onto domestic flights in Brazil); a light sweater for evening if you go in winter, sturdy shoes, binoculars, light long-sleeve shirts and pants for canoe rides in the full sun. You may want to bring life jackets for small children: The Refugio supplies them but its kid sizes are large and bulky. The current is too strong for even good small swimmers to navigate solo.

Where to stay

Refugio da Ilha: It offers fantastic meals, comfortable accommodation, and two wildlife excursions a day by boat, canoe, foot, horseback or jeep for $330 a person. It's an easy 3 1/2-hour drive from Campo Grande airport, or the lodge will arrange transport for you. refugiodailha.com.br

Hotel Barra Mansa: This popular lodge option in the Southern Pantanal is harder to reach – which means you're further into the wilderness – but the price of the extra isolation is a six-hour drive on a dirt road or, through much of the year when the water is high, a small-plane flight that costs another $1,000 for five passengers. The aerial view of the Pantanal is a spectacular bonus. hotelbarramansa.com.br

Caiman Ecological Refuge: This luxury lodge does not accept children, and is also about a three-hour drive from Campo Grande. caiman.com.br

Stephanie Nolen is The Globe and Mail's Latin America correspondent.