The Petén department is bordered on the east by
Belize and by
Mexico (with the Mexican states of
Chiapas to the west,
Tabasco to the northwest and
Campeche to the north). Its northwest border includes the border town of El Ceibo, Guatemala, adjacent to El Ceibo, Tabasco, Mexico. To the south it borders the Guatemalan departments of
Alta Verapaz and
Izabal. Much of the western border with Mexico is formed by the
Usumacinta River and its
tributary the
Salinas River. The area is crossed by low east–west oriented ridges of
Cenozoic limestone and is characterised by a variety of forest and soil types; water sources include generally small rivers and low-lying seasonal swamps known as
bajos. A chain of fourteen lakes runs across the
central drainage basin of the Petén; during the
rainy season some of these lakes become interconnected. This
drainage area measures approximately east-west by north-south. The largest lake is
Lake Petén Itza, near the centre of the drainage basin; it measures . A broad
savannah extends south of the central lakes; it features a compact red clay soil that is too poor to support heavy cultivation. This resulted in a relatively low level of
pre-Columbian occupation. The savannah has an average altitude of
above mean sea level with karstic ridges reaching an average altitude of . The savannah is surrounded by hills with unusually steep southern slopes and gentler northern approaches; the hills are covered with dense tropical forest. To the north of the lakes region
bajos become more frequent, interspersed with forest. In the far north of the Petén the
Mirador Basin forms another interior drainage region. To the south Petén reaches an altitude of approximately as it rises towards the
Guatemalan Highlands and meets
Paleozoic metamorphic rocks. The main bodies of standing water in the department are the lakes
Petén Itzá,
Peténchel,
Quexil,
Salpetén and
Macanche in the centre of the department;
Yaxhá and
Sacnab in the east,
Petexbatún in the southwest, and
Perdida,
Larga,
La Gloria,
San Diego,
Mendoza,
El Repasto and
Lacandón in the west. ==Climate==