Madidi is a place like no other on Earth, where the Andes meet the Amazon, and icy peaks plunge straight down to steamy jungles.
"Imagine a place which starts with that kind of landscape and goes all the way down to lush tropical forests," says British biologist Rob Wallace.
"Finding a new species is always a big deal. Finding a new species of mammal, which many people find more inspirational, is a big deal. And finding a new species of monkey is a huge deal."
This spectacular Bolivian wilderness is Wallace's outdoor laboratory. And after a decade of grueling travel and exploration for New York's Wildlife Conservation Society, Wallace has discovered something most scientists can only dream of.
60 Minutes asked Wallace to lead it to the monkeys, on a trip that quickly turned into a remarkable adventure. Just getting there became a vital part of the story.
Dropping through five different climate zones, the trip passed some of the most amazing animals on Earth, like the world's biggest flying creature with a 10-foot wingspan.
"That was an Andean Condor. They're huge, much bigger than I can make with my hands, much bigger," says Wallace. "Sometimes, they fly past really low, and they're incredibly impressive."
The final destination was the largely unexplored national park called Madidi. For 100 miles, only wild rivers cut through Madidi's jungles and gorges.
"It's just completely empty," says Amanpour. "I feel like we're the only people on Earth here."
But it's not the scenery that makes Madidi so extraordinary. Although it's only the size of New Jersey, Wallace believes that in terms of animal life, Madidi may be the richest place on Earth.
"It's a good place to see otters and tapir, cayman, which are South American crocodiles, and capibara, which are the largest rodents in the world," says Wallace.
"Madidi is the most biologically diverse park in the world. If we think of birds, we estimate that eventually there'll be 1,100 species of birds actually in the park, and that's more bird species than there are in the whole of North America, for example. So that makes Madidi very special."
As visitors push even farther into the wilderness, the river gets dangerously shallow. Wallace says the crew has to get out and push. Ladies are excused. The Bolivian park rangers try their best to sound out the hidden dangers, but they can't avoid every obstacle.
After hours of weaving up the Tuichi River, the team finally gets to the wilderness trail that it's been looking for. Now begins the trek through miles of almost impenetrable jungle.
"There's a flat bit, then there's a hilly bit, then there's another flat bit," says Wallace.
"You make it sound so easy," says Amanpour. "It is water and mud and disgusting."
It's just the way the wild pigs like it, and a loud clicking sound is the first clue that they may be in the area.
"That's the clicking of the jaws. It's like a warning sign. So they know something is up; they are beginning to smell us," says Wallace. "The noises we hear, the sort of clacking of the jaws, come from breaking tough nuts, palm nuts, because they've got great big teeth. We've seen herds of 250, 300 animals."
Theoretically, Wallace says, you can get stampeded. And that's exactly what happened. "Everyone always says you have to look for a tree to climb, but so far we've always been okay," says Wallace.
Hours later, the group finally stumbles into Wallace's research station, near where he found the monkey. They are just ahead of a tropical downpour that threatens to spoil the attempt to confirm his discovery.
After nearly four hours on the river, and a grueling four-and-a-half hour trek by foot, the group got up at the crack of dawn to start searching for the new monkey. The rain stopped them.
The deluge stopped by the afternoon, and they were able to start a search in a place where humans are the exotic species.
Have there been times when it's just been too hard?
"Yeah, there are risks. There are things in the forest you are not gonna see in Manhattan," says Wallace. "But there are things in Manhattan that you are not gonna see in the forest, either."
When do you learn to stop looking at your feet and actually look around?
"It takes a while because there are all sorts of hazards," says Wallace. "But after a while, you get used to it, and you can pay attention to what's around you."