Sprawling across the eastern slope of the Andes, the Manu Biosphere Reserve (Reserva de Biósfera del Manu) is one of the most biodiverse corners of the planet. Roughly the size of New Hampshire, Manu Biosphere Reserve begins at high-altitude grasslands at 4,100 meters, drops through cloud forest and mountainous rainforest, and then fans across a huge swath of rainforest at around 350 meters.
There are 13 species of monkeys here (more than anywhere else in the country), 15,000 plants, 1,300 butterflies, and more than a million insects that have not been even close to documented.
In May and June, the beginning of the colder and dry season, the odds increase of seeing jaguars, which come out to sun themselves on river logs. From July to November, near the end of the dry season, macaws, parrots, and parakeets are especially abundant around the riverside clay licks.
Other frequently seen megafauna include giant otters, black caimans, tapirs, armadillos, anteaters, sloths, wild pigs, and the endangered harpy eagle. As if that were not enough, Manu is one of world’s top birding spots, with more than 1,022 confirmed species—almost 15 percent of the world’s total!
The Parque Nacional Manu was created in 1973, but the area was deemed so biodiverse that UNESCO incorporated the whole surrounding area into a biosphere in 1977. Then Manu won the ultimate accolade when the International Union for the Conservation of Nature declared it a World Heritage Site, one of only 200 in the world.
These days the biosphere is classified into several areas. The section along the Río Alto Madre de Dios is the Multiple Use Zone (commonly referred to as the Cultural Zone or Buffer Zone), where there are a few villages and a variety of ecolodges. The more pristine section up the Río Manu is the Parque Nacional Manu, to which access is strictly controlled. To enter the area, travelers must be with one of Manu’s licensed operators , who have built comfortable safari camps (and one lodge) alongside oxbow lakes. The lower part of the Río Manu, formerly known as the Reserved Zone, is used for sustainable ecotourism and research.
The vast majority of the 1.5-million-hectare Parque Nacional Manu is closed off to everyone but licensed biologists and anthropologists. This chunk of rainforest shelters at least two ethnic groups who have had almost no contact with western civilization, the Kogapacori and the Mashco Piro. Other groups have only limited contact with the modern world.
Only a handful of companies are allowed to operate in Parque Nacional Manu. They offer trips from 5 to 10 days that range from US$600 for camping to US$2,250 for more comfortable, high-end tours that include lodges with cotton sheets, electricity, and hot water. Some of the agencies are offering new adventure options, from rafting and trekking to extreme mountain biking and even llama-cart touring.
Apart from the eight operators listed here , many other Cusco agencies sell Manu trips. Some of these agencies simply “endorse” their clients over to a licensed Manu operator at an additional cost. Others only take passengers through the Cultural Zone of the park, which is cheaper because there is no US$45 park fee and less gas is used. You will have better guides, see more wildlife, and be more comfortable if you stick with one of the eight operators listed here, who also offer budget options.
It is not recommended to visit Manu on your own or with a private guide. Boat traffic is highly sporadic, and without one of the licensed agencies, the rangers absolutely will not allow you into the Parque Nacional Manu.
The best time to visit Manu is during the dry season May–October, though rains only become unbearably heavy during January and February. Considering how hard Manu is to reach, it does not make sense to go for less than six days—except for those who fly in and out of Boca Manu and choose to bypass the cloud forest.
One of the best parts of Manu is getting there and dropping through the dizzying sequence of ecosystems along the way. The first day is spent either driving seven hours through the altiplano near Cusco  or flying in a small-passenger plane over the Andes and down into the jungle. The driving option takes you to one of a handful of lodges perched in the cloud forest and surrounded with orchids, hummingbirds, butterflies, and the crimson Andean cock of the rock. From there, visitors descend to the lower jungle that same morning and take a several-hour boat ride down the Río Alto Madre de Dios.
The flying option skips the bus and boat rides, dropping passengers directly into the small town of Boca Manu and its tiny Aerodrome airport. The landing strip lies at the junction of the Madre de Dios and Manu Rivers. There are two lodges here, but the highlight for most people is heading up the slow-moving Río Manu into the park or cruising the Río Madre de Dios into the Cultural Zone.
In the national park, guests commonly stay in safari camps, but in both national park and Cultural Zone trips, participants spend their days exploring oxbow lakes with floating platforms and spotting scopes.
Most companies return to Cusco by air. Air service into Boca Manu unfortunately continues to be irregular and unpredictable. Flights are often postponed because of rain, and passengers are sometimes bumped at the last minute because of overbooking and other issues. Check with your agency for information about how they will handle delayed or postponed flights from Boca Manu.
To avoid the potential complications of flying and to reduce costs, a few operators are backtracking all the way up the Río Madre de Dios to return to Cusco  by road. Other agencies are continuing down the Río Madre de Dios to the gold rush town of Boca Colorado, which is an eight-hour drive to Puerto Maldonado’s airport. Either of these overland options is a grueling one-day combination of boats and trucks.
A shorter option, offered by Manu Expeditions , is a trip farther down the Río Madre de Dios by boat to Laberinto and then on to Puerto Maldonado  via car. This latter option can take as little as eight hours. Regardless, these options are bundled with trips of seven days or more, or may be used if the flights are shut down for any reason.