Buenos Aires is a municipality in the Rivas department of Nicaragua. It is located on the western shore of Lake Nicaragua, the largest lake in Central America.
The municipality lies in the southwestern part of the country, within the Rivas department, a region that borders the Pacific coast to the west and Lake Nicaragua to the east. Its position on the lake's western shore places it among the lakeside communities of the department.
Buenos Aires is one of several municipalities that make up the Rivas department. It shares its name with the capital of Argentina, but it is a distinct and much smaller settlement in Nicaragua.