Lima and Callao Metropolitan Area in the context of "List of metropolitan areas by population"

The Rímac River [ˈri.mak] is located in western Peru and is the most important source of potable water for the Lima and Callao Metropolitan Area. It belongs to the Pacific Slope, into which it flows after bathing the cities of Lima and Callao, together with the Chillón River, to the north, and the Lurín River, to the south. It is 204 km long and has a basin of 3,312 km², of which 2,237.2 km² is a humid basin. The basin has a total of 191 lagoons, of which only 89 have been studied. The river begins in the highlands of the Huarochirí Province in the Lima Region and its mouth is located in Callao, near Jorge Chávez International Airport.

The river runs through the Rímac Valley (Spanish: Valle del Rímac), one of three valleys in the city of Lima. The city of Lima is located on the delta-shaped valley, as are various towns such as Matucana, Ricardo Palma, Chosica, Chaclacayo and Vitarte, small cities that function as strategic points between the coast and central mountains of Peru. It has a total surface of 3,700 km.