Taking travelers to the scenic, wildlife-rich (and, in the north, mosquito-free) Rio Urubú, Antonio Gomes runs some of the region's best tours. Depending on water levels, you can hike deep into primary forest, canoe quietly through the flooded forest, visit local communities, fish for piranhas and spend time out on the Amazon itself.

He has two excellent lodges and a range of flexible packages that can last anywhere from a couple of days to a week. Slightly pricier, but worth it.