Cachoeira do Arari is a Brazilian municipality located in the state of Pará. Its population as of 2020 is estimated to be 24,064 people. The area of the municipality is 3,102.080 km². The city belongs to the mesoregion Marajó and to the microregion of Arari.
The municipality is contained in the 59,985 square kilometres (23,160 sq mi) Marajó Archipelago Environmental Protection Area, a sustainable use conservation unit established in 1989 to protect the environment of the delta region.[2]