Peru occupies 1,285,216 square kilometers on the western edge of South America, bordered by Ecuador and Colombia to the north, Brazil to the east, Bolivia to the southeast, Chile to the south, and 2,414 kilometers of Pacific Ocean coastline to the west. The country divides into three distinct geographical zones running north to south: the coastal desert strip, the Andean highlands, and the Amazon basin. This vertical geography compresses ecological diversity into a territory approximately twice the size of Texas, creating climatic extremes that range from hyperarid coastal plains receiving less than 2 millimeters of annual rainfall to rainforest regions where precipitation exceeds 3,000 millimeters per year.
The Andes Mountains dominate Peru's topography, running the entire length of the country in parallel ranges called cordilleras. The Cordillera Blanca in Ancash region contains the highest concentration of tropical glaciers on Earth, with Huascarán rising to 6,768 meters as Peru's tallest peak and the fourth highest in the Western Hemisphere. The Cordillera Huayhuash, lying south of the Cordillera Blanca, presents a compact massif of peaks exceeding 6,000 meters within a 30-kilometer circuit. Between these western cordilleras and the eastern ranges flows the Marañón River, carving canyons that reach depths exceeding 3,000 meters. The Colca Canyon near Arequipa descends 3,270 meters at its deepest point, while the Cotahuasi Canyon reaches 3,535 meters, making it one of the world's deepest land canyons measured from rim to river. These measurements exceed the Grand Canyon's maximum depth of 1,857 meters.
The coastal region, called La Costa, extends 40 to 180 kilometers inland from the Pacific and comprises approximately 11 percent of Peru's territory. This desert strip results from the Humboldt Current, which flows northward along the coast carrying cold Antarctic water that creates a temperature inversion preventing rainfall. The Sechura Desert in northwestern Peru represents the southernmost extension of South America's coastal deserts, while the Nazca Desert in the Ica region hosts the Nazca Lines, geoglyphs etched into the pampas between 500 BCE and 500 CE across 450 square kilometers. Coastal temperatures remain moderate year-round, with Lima averaging 15-19°C in winter months from June through September and 21-26°C in summer months from December through March. Coastal humidity stays consistently high, often exceeding 80 percent, creating a phenomenon called garúa—a persistent mist that blankets Lima and other coastal cities from May through November without producing measurable rain.
The Andean highlands, or Sierra, occupy 30 percent of Peru's area and contain most of the country's population centers above 2,000 meters. Cusco sits at 3,399 meters, Puno at 3,827 meters, and Huaraz at 3,052 meters. These elevations create highland climates with pronounced diurnal temperature variation. In Cusco, daytime temperatures during the dry season from May through September typically reach 18-20°C, dropping to near freezing at night. The wet season from November through March brings afternoon rains that account for 80 percent of annual precipitation, which totals approximately 700 millimeters in Cusco but varies dramatically with elevation and exposure. The altiplano—high plateau regions above 3,800 meters—experiences harsher conditions, with Puno receiving approximately 600 millimeters of annual rainfall concentrated almost entirely between December and March.
Lake Titicaca straddles the Peru-Bolivia border at 3,812 meters elevation, making it the highest navigable lake of significant size on Earth. The lake covers 8,372 square kilometers, with Peru controlling 4,996 square kilometers on the northwestern portion. Maximum depth reaches 281 meters in the lake's northeastern section. The Titicaca basin experiences a modified highland climate, with the lake's thermal mass moderating temperature extremes. Water temperatures remain between 10-14°C year-round, while air temperatures in lakeside communities like Puno range from 1-15°C during winter months and 5-16°C during summer. The lake receives inflow from more than 25 rivers, with the Ramis River providing approximately 30 percent of total input. Only the Desaguadero River provides outflow, draining southeast toward Bolivia's Lake Poopó and accounting for less than 10 percent of water loss—the remainder evaporates.
Eastern Peru transitions from Andean peaks into the Amazon basin across a series of ecological zones collectively called the Selva, which occupies 60 percent of national territory. The eastern Andean slopes, or Selva Alta, descend from approximately 3,500 meters to 600 meters over horizontal distances that compress to as little as 50 kilometers in some regions. This dramatic elevation change creates montane cloud forests receiving 2,000-3,000 millimeters of annual rainfall distributed relatively evenly throughout the year. Machu Picchu, located at 2,430 meters on the eastern Andean slope above the Urubamba River, occupies this cloud forest zone. The region experiences two seasons: a drier period from May through September when monthly rainfall averages 40-80 millimeters, and a wetter period from November through March when monthly totals exceed 150 millimeters and can reach 250 millimeters in January and February.
The lowland Amazon, or Selva Baja, extends across northeastern Peru at elevations below 600 meters. Iquitos, Peru's largest Amazon city, sits at 106 meters elevation where the Itaya and Nanay rivers join the Amazon River. The city remains accessible only by air or river, with no road connections to the rest of Peru. Iquitos receives approximately 2,700 millimeters of rainfall annually, with the heaviest rains from January through May when monthly totals exceed 250 millimeters. Temperatures remain uniformly hot year-round, with daily maximums consistently between 30-33°C and minimums between 20-23°C. Humidity exceeds 80 percent throughout the year. The Amazon River itself forms in Peru through the confluence of the Marañón and Ucayali rivers near the town of Nauta, approximately 100 kilometers southwest of Iquitos. From this confluence point, the river flows 3,200 kilometers northeast through Brazil to the Atlantic Ocean.
The Marañón River, one of the Amazon's principal sources, originates in the Cordillera of the Andes at approximately 5,800 meters elevation in the Huánuco region. It flows 1,600 kilometers through northern Peru, carving the Marañón Canyon before joining the Ucayali. The Ucayali River forms from the confluence of the Apurímac and Urubamba rivers in the Ucayali region and flows 1,600 kilometers northward. The Apurímac River, considered by some geographers as the Amazon's most distant source, originates from Nevado Mismi in the Arequipa region at approximately 5,200 meters elevation. The Urubamba River, flowing through the Sacred Valley past Ollantaytambo and Machu Picchu, descends from Andean glaciers above 4,000 meters and travels approximately 700 kilometers before joining the Apurímac. These river systems drain the eastern Andean slopes and unite in complex patterns across the Selva Baja.
Major tributaries entering the Ucayali-Amazon system include the Tambopata River and Madre de Dios River in southeastern Peru. The Tambopata originates in the Puno region and flows approximately 400 kilometers northeast through Madre de Dios department, passing through Tambopata National Reserve before joining the Madre de Dios River. The Madre de Dios River itself flows approximately 1,150 kilometers from its source in the Cusco region, crossing into Bolivia and eventually joining the Madeira River, a major Amazon tributary. These southeastern rivers drain territory encompassing some of the Amazon's highest biodiversity zones, where Andean foothills meet lowland rainforest.