As municipal seat, the city of Petatlán is the local governing authority for over 730 named communities, with a combined territory of (inegi). About half of the municipality's population of 44,485 people live in the city proper.(inegi) Outside the seat, the most populous are San Jeronimito, Coyuquilla (norte), Palos Blancos and El Mameyal. The municipality borders the municipalities of
Coyuca de Catalán,
Tecpan de Galeana and
Teniente José Azueta with the Pacific Ocean on the south side. The geography of the area consists of rugged mountains, semi-flat areas and flat areas, which are part of the Costa Grande region. Rugged mountains cover about 70% of the surface, mostly in the north and center, formed by the Sierra Madre del Sur and reach a height of
above sea level. Semi-flat areas cover about 20% of the surface and are mostly located just north of Highway 200 and are mostly rolling hills. Flat areas cover the rest and are concentrated in the west, southeast and the coastline. Major rivers are the Coyuquilla, Petatlán and San Jeronimito, with a number of arroyos such as the Camotal, La Morena, El Comalate and Coyuca. There are small lakes and lagoons such as the Santiago, Estero Valentín, Salina el Cuajo and Tular. The variations in altitude lead to three types of climate: semi-humid, semi-hot and hot. The first is mostly located in the north along the border with Coyuca de Catalán. The second is in the center and the last is along the coast. In all these climates, there is a rainy season, which lasts from June to October. There are also rains in November and December. Most of the vegetation is low- and medium-altitude rain forest, whose trees often lose their leaves in the late fall. At the highest elevations, there are forests of
pine and
holm oak. Wildlife include
deer,
iguanas,
rabbits,
armadillos,
tejon,
raccoons,
opossums,
skunks,
wild cats,
buzzards, various types of
parrots and other birds. The forests contains harvestable species such as
black sapote,
ceiba,
white oak,
mahogany and
red cedar. The municipality has a number of beaches including El Mirador, El Cayatal, Valentìn, La Barrita and Juluchuco. El Valentin has a lagoon. ==Population and infrastructure==