Cruzeiro do Sul (Portuguese pronunciation: [kɾuˈzejɾu du ˈsuw], Southern Cross) is a municipality located on the Juruá river in the west of the Brazilian state of Acre. It is the second-largest city in Acre.
It is bordered to the north by the state of Amazonas, to the south by Peru, to the east by the municipality of Porto Walter, to the west by the municipality of Rodrigues Alves, to the northwest by the municipality of Tarauacá, and to the northwest by the municipality of Mâncio Lima.
The municipality contains 23% of the 846,633 hectares (2,092,080 acres) Serra do Divisor National Park, created in 1989.