Managua, with an estimated population of over 1 million, is the capital of Nicaragua and is located on the Central American volcanic axis. Five large, water-filled calderas show the northwest-southeast alignment of this single range of volcanoes through the region. The single smoke plume seems to emanate from an unnamed fissure vent west of the water-filled Nindire Caldera and Masaya Caldera (the larger, roughly circular feature east of the smoke). A radial drainage pattern west of the smoke indicates forested slopes on the flanks of a much older volcano. Two water-filled calderas appear on the peninsula northwest of Managua. The two large bodies of water—part of Lake Managua (north of Managua) and the northwestern part of Lake Nicaragua (east edge of the photograph)—are two freshwater lakes connected by a short river that flows from Lake Managua into Lake Nicaragua, ultimately emptying into the Caribbean Sea. Visible are airport runways (north margin of the photograph) and agricultural fields, many of which have circular irrigation patterns, in the fertile garden valley (northeast corner of photograph).