Guatemala covers 108,889 km² at the northern end of Central America, bordered by Mexico, Belize, Honduras and El Salvador, with about 400 km of coastline in all, on the Pacific and on the Gulf of Honduras in the Caribbean. Its geography falls into three main regions: a mountainous highland core, where two ranges cross the country from west to east; a hot Pacific coastal plain south of the mountains; and the low limestone plateau of Petén in the north, which makes up about a third of the country. The highest point is Volcán Tajumulco in San Marcos department, the highest mountain in Central America, at 4,203 m (some sources give 4,220 m). The main rivers are the 486 km Motagua, whose basin is the largest in the country, which drains to the Caribbean; the Usumacinta and its tributaries, which drain Petén toward the Gulf of Mexico; and the Polochic and Río Dulce, which pass through Lake Izabal, the largest lake. About 17.6 million people live there, and most of the major cities are in the highlands. The clearest way to see how these pieces fit together is to cross the country by road, from the Mexican border in the west to the Caribbean and then north into the forest.
La Mesilla to Huehuetenango, Beneath the Cuchumatanes
Central American Highway 1, or CA-1, the Guatemalan section of the Pan-American Highway, begins at the La Mesilla border crossing in Huehuetenango department and runs across the highlands toward the capital. The first great landform it meets is the Sierra de los Cuchumatanes, the highest non-volcanic mountain range in Central America. The range covers about 16,350 km² of Huehuetenango and El Quiché departments and rises from about 500 m to 3,837 m at its highest peaks; some 1,500 km² lies above 3,000 m, making it the most extensive highland region in the isthmus. Its western and southwestern edge is marked by the Seleguá River, which separates it from the volcanic Sierra Madre to the south.
The Cuchumatanes are not volcanoes. They are a block of Cretaceous marine limestone lifted high by faulting along the northern edge of the Caribbean Plate, and their top, the Altos de Chiantla, is a table-shaped karst plateau of sinkholes and underground drainage. At that height the vegetation looks more like the Andes than the rest of Mesoamerica, with páramo grassland, juniper, pine and fir. The climate there is cold as well, grading from temperate on the lower slopes to freezing on the highest ground of the range.
Toward Quetzaltenango: Santa María and the Sierra Madre Volcanoes
South and east of Huehuetenango the road climbs onto the second mountain system, the Sierra Madre, a chain of steep volcanic cones running parallel to the Pacific. All 37 of Guatemala's volcanoes stand in this chain, formed as the Cocos Plate dives beneath the Caribbean Plate. Off the route to the southwest, in San Marcos, rises Tajumulco, a stratovolcano of andesite and dacite with two summits, the eastern one topped by a crater 50 to 70 m wide. Its last eruption date is unknown.
A little farther along, the highway passes the turning to Quetzaltenango, the country's main western highland city at about 2,350 m. Above it looms Santa María, a cone that rises about 1,400 m over the plain on which the city sits. Dormant for at least 500 years, it erupted on 24 October 1902 in one of the three largest eruptions of the 20th century, rated 6 on the Volcanic Explosivity Index and ejecting an estimated 8 km³ of magma. Pumice fell over some 273,000 km², coffee plantations on its slopes were destroyed, and the blast tore open a crater about 1 km across on the volcano's southwest flank. The lava dome complex that has grown in that crater since 1922, Santiaguito, is one of Guatemala's three active volcanoes today.
Above Lake Atitlán, Inside a 79,500-Year-Old Caldera
East of Quetzaltenango the highway runs along high ground north of Lake Atitlán, in Sololá department. The lake fills a caldera, a collapsed volcanic crater, created by the Los Chocoyos supereruption about 79,500 years ago, which ejected up to 300 km³ of tephra and scattered ash from Florida to Ecuador. Volcanic activity here began about 11 million years ago, and the basin has gone through four cycles of volcano growth and collapse.
The result is the deepest lake in Central America: about 18 km by 8 km, covering 130.1 km², with a maximum depth of about 340 m and an average of 154 m. It has no outlet to the sea; two rivers feed it and the water leaves by other means. Three younger volcanoes have grown since the collapse: San Pedro and Tolimán inside the caldera and Atitlán on its southern rim, which last erupted in 1853. Tz'utujil and Kaqchikel Maya towns line the steep escarpments around it, farming coffee, avocado, corn and onions on the slopes.
Chimaltenango to Guatemala City: Fuego and a Valley Built by Faults
From Chimaltenango, CA-1 descends toward the capital. To the south, about 16 km west of the colonial city of Antigua, Volcán de Fuego erupts almost continuously at a low level, with small bursts of gas and ash every 15 to 20 minutes and larger eruptions in recent years, including June 2018. Fuego is joined to Acatenango on its north; between them lies La Meseta, the scarp of an older volcano that collapsed about 8,500 years ago, after which Fuego began to grow. Pacaya, 2,552 m high and erupting frequently since 1961 after 70 quiet years, is the third of Guatemala's persistently active volcanoes.
Guatemala City, at about 1,500 m, sits in a different kind of landform: a graben, a strip of crust dropped down between faults. Movement along the plate boundary to the north has opened a series of north–south grabens across the region, and the capital's is one of them, which adds to its earthquake risk. The city's growth and its ravines are covered in our guide to Guatemala City, the capital.
Down the Motagua Valley on CA-9
East of the capital the route switches to CA-9, the highway that runs from the Pacific port of Puerto San José through Guatemala City to Puerto Barrios on the Caribbean, 297 km northeast of the capital. It follows the valley of the Motagua River, which rises in the western highlands and flows 486 km east to the Gulf of Honduras, draining a basin of 12,670 km², the largest in Guatemala. Its last few kilometres form part of the border with Honduras.
The valley is a plate boundary. The Motagua Fault, about 350 km long and the longest in the country, is the main line of contact between the North American and Caribbean plates, the two sliding past each other sideways. On 4 February 1976 it ruptured along about 230 km in a magnitude 7.5 earthquake that killed about 23,000 people. The valley also holds the only known source of jadeitite (jade) in Mesoamerica, worked by the Olmec and Maya, and the Maya city of Quiriguá stands near the river's north bank.
Walled in by the Sierra de las Minas, up to about 3,000 m, on the north and the Sierra del Merendón on the south, the valley receives relatively little rain. It is one of the driest places in Central America, with less than 500 mm of rain a year, temperatures up to 50 °C and a thornscrub of cactus and acacia covering about 2,330 km².
Lake Izabal and the Río Dulce Gorge
Near the Caribbean the landscape turns wet and green. Lake Izabal, the country's largest lake at 672 km², is only about a metre above sea level and no more than 18 m deep; the Polochic River, which flows 194 km east through a deep valley, is the largest river draining into it. The lake empties through the Río Dulce, whose entrance is guarded by the Castillo de San Felipe de Lara, a Spanish fort built in 1652 against pirates. Just after the river leaves the lake, one of the biggest bridges in Central America spans it at the town of Fronteras, usually called Río Dulce.
Downstream the river widens into El Golfete, a lake about 16 km long where West Indian manatees shelter in the brackish water, then meanders for 10 km through a gorge whose sides rise up to 91 m and are covered with teak, mahogany and palms, before reaching the Caribbean near the Garifuna town of Livingston, the country's main Caribbean port before Puerto Barrios was built. Puerto Barrios, the end of CA-9 and Guatemala's main Caribbean port, lies a short way along the coast.
North to Flores and the Petén Lowlands
The last leg of the crossing turns north into Petén, the largest department at 35,854 km², about one third of Guatemala but home to only about 596,000 people in 2018. The mountains give way to a low, densely forested limestone plain with karst features, crossed by low east–west ridges and dotted with seasonal swamps called bajos. Much of the western border with Mexico follows the Usumacinta River and its tributary, the Salinas.
The journey ends at Flores, the departmental capital, built on an island in Lake Petén Itzá. The lake is 99 km² and up to 160 m deep, with no surface outflow; it loses water mainly by evaporation yet is not salty. About 64 km by road to the northeast lies Tikal, inside the Maya Biosphere Reserve, created in 1990 and covering 21,602 km², roughly a fifth of the country, to protect the largest area of tropical forest left in the Americas north of the Amazon. From the cold karst of the Cuchumatanes to this lowland forest, the crossing touches every major region of the country except the Pacific coastal plain, and the frontiers it touches along the way are traced in our guide to the countries that border Guatemala.