"Mamirauá" means "baby manatee" in the local native language, and the reserve is named after the Amazonian Manatee (Trichesus inunguis). Manatees are Monica's favorite animals. So it must have been fate that brought us to Mamirauá -- we didn't know the origin of the word before our visit.
Unfortunately, we discovered that it's next to impossible to see an Amazonian Manatee in the wild. They are sparsely distributed, and they are very shy, and the water is mostly opaque, and they only come up to the surface from time to time for quick snootfulls of air. We were told of researchers who had studied these manatees for years without ever seeing one.
Fortunately, we had visited the Instituto Nacional de Pesquisas da Amazônia (INPA) in Manaus before visiting Mamirauá. The INPA temporarily houses a number of manatees that have typically been rescued after encounters with local fishermen. Monica enjoyed their company, and they seemed to enjoy her company also.