Iran occupies 1,648,195 square kilometers on the Persian Plateau, making it the seventeenth largest country by total area. The plateau itself sits at an average elevation of 1,200 meters above sea level, bordered by two discontinuous mountain chains that define the country's physical geography. The Alborz Mountains trace the southern Caspian Sea shoreline in a narrow arc roughly 600 kilometers long, while the Zagros Mountains sweep northwest to southeast for approximately 1,500 kilometers from the border with Turkey to the Strait of Hormuz. Between these ranges lies the central basin, occupied primarily by the Dasht-e Kavir and Dasht-e Lut, two deserts that together cover roughly one-sixth of Iran's total land area.
Mount Damavand rises to 5,610 meters in the central Alborz range, 66 kilometers northeast of Tehran. The volcano last erupted in approximately 5350 BCE based on geological surveys of pyroclastic deposits. Damavand remains a dormant stratovolcano with fumarolic activity near its summit crater. The mountain holds permanent snow above 4,200 meters year-round. Sabalan, another volcanic peak in northwestern Iran near Ardabil, reaches 4,811 meters. The Zagros system contains no volcanic peaks but includes more than 1,500 individual mountains, with Zard-Kuh reaching 4,548 meters in Chaharmahal and Bakhtiari Province. The Zagros formed through the collision of the Arabian Plate with the Eurasian Plate, a process ongoing at approximately 25 millimeters per year according to GPS measurements.
The Caspian Sea forms Iran's entire northern border for 650 kilometers, from Astara in the northwest to the Turkmenistan border in the northeast. The Caspian lies 28 meters below global mean sea level, making it the lowest elevation point in Iran. Water levels have fluctuated by more than two meters in the past century, with significant drops recorded since the 1990s. The Mazandaran and Gilan provinces along the Caspian coast receive between 1,000 and 2,000 millimeters of annual precipitation, contrasting sharply with the interior plateau. The southern coastline extends approximately 1,800 kilometers along the Persian Gulf and 750 kilometers along the Gulf of Oman, giving Iran total maritime borders of roughly 3,200 kilometers. The Strait of Hormuz, at its narrowest point between Iran and Oman, measures 39 kilometers across.
The Dasht-e Lut received UNESCO World Heritage designation in 2016 as Earth's hottest land surface, where NASA satellite measurements recorded ground temperatures of 70.7 degrees Celsius in 2005. The desert covers approximately 51,800 square kilometers in southeastern Iran across Kerman and Sistan-Baluchestan provinces. Kaluts, wind-sculpted ridges of sand and rock, extend for dozens of kilometers in parallel formations reaching heights of 80 meters. The Dasht-e Kavir, covering roughly 77,600 square kilometers in north-central Iran, contains extensive salt flats and seasonal marshes called kavirs. Both deserts remain virtually uninhabited except for scattered settlements along their margins. The Maranjab Desert on the Kavir's western edge contains caravanserais dating to Safavid rule in the seventeenth century.
Lake Urmia in northwestern Iran once ranked as the world's sixth largest saltwater lake, spanning approximately 5,200 square kilometers in the 1990s. Declining rainfall, dam construction on feeder rivers, and agricultural water extraction reduced the lake to roughly 10 percent of its former area by 2014. Satellite imagery from the Iranian Space Agency documented the lake's surface area at 1,000 square kilometers in 2013. Restoration efforts beginning in 2015 increased water levels modestly, with the lake reaching approximately 2,500 square kilometers by 2019 according to government reports. The lake's salinity exceeds 340 grams per liter in remaining water bodies, compared to approximately 35 grams per liter in ocean water. Bakhtegan Lake in Fars Province similarly contracted from approximately 3,500 square kilometers in the 1970s to intermittent dry beds by 2010.
The Karun River, originating in the Zagros Mountains, flows 950 kilometers before emptying into the Shatt al-Arab waterway at the Iraq border. It remains Iran's only navigable river, though only for the final 180 kilometers from Ahvaz to the confluence. The river carries an annual flow of approximately 20 billion cubic meters, making it Iran's most water-rich river by volume. Multiple dams interrupt the Karun's course, including the Karun-3 Dam completed in 2005 with a generating capacity of 2,000 megawatts. The Zayandeh River in central Iran flows 405 kilometers from the Zagros to the Gavkhouni wetland southeast of Isfahan, though reduced flow frequently prevents water from reaching the terminus. Seasonal rivers called qanats historically provided irrigation across the plateau through underground channels, with UNESCO recognizing the Persian Qanat system in 2016 for eleven representative sites.
Qeshm Island in the Strait of Hormuz covers 1,491 square kilometers, making it the largest island in the Persian Gulf. UNESCO designated the island a geopark in 2006, the first such designation in the Middle East. The Chahkooh Canyon cuts through sedimentary rock layers, creating passages up to 100 meters deep. Stars Valley features erosional pillars and spires formed in Miocene-era limestone. The Hara mangrove forests on Qeshm's northern coast cover approximately 100 square kilometers and host migratory bird populations exceeding 200 species according to surveys by the Iranian Department of Environment. Kish Island, 19 kilometers southwest of Qeshm, covers 91 square kilometers and functions as a free trade zone established in 1989. Hormuz Island, 8 kilometers off the mainland, displays soils colored red, yellow, and ochre from iron oxide and other mineral content.
The Hyrcanian Forests along the Caspian coast received UNESCO recognition in 2019 as a serial property covering 850 square kilometers across fifteen protected areas. These temperate broadleaf forests date to the Tertiary period, approximately 25 to 50 million years ago, predating the Quaternary glaciation. The forests contain relict species including the Caspian tiger, extinct in Iran since the 1960s, and the Persian leopard, with population estimates of fewer than 1,000 individuals remaining nationwide according to 2017 surveys. The forests experience annual precipitation between 1,400 and 2,000 millimeters and contain tree species including Caucasian oak, oriental beech, and Caspian alder. Golestan National Park in the northeastern Hyrcanian zone covers 874 square kilometers and contains elevation gradients from 450 to 2,411 meters.
Kavir National Park, established in 1964, protects 4,000 square kilometers of desert and semi-desert landscape in Semnan Province. The park contains populations of Persian onager, also called gur, a wild ass subspecies with fewer than 500 individuals surviving in Iran based on 2016 census data. Caracal, sand cat, and Asiatic cheetah historically ranged through the park, though cheetah sightings ceased in Kavir during the 1980s. The Asiatic cheetah, now critically endangered with an estimated population of fewer than 50 individuals nationwide, survives primarily in Touran National Park and Miandasht Wildlife Refuge according to the Iranian Cheetah Society. Tandoureh National Park in Khorasan Razavi Province covers 355 square kilometers along the Turkmenistan border and contains wild sheep populations including urial.
The Arasbaran Protected Area in East Azerbaijan Province encompasses approximately 7,280 square kilometers of mountainous terrain ranging from 700 to 3,100 meters elevation. UNESCO designated Arasbaran a biosphere reserve in 1976. The area contains deciduous forests transitioning to steppe grasslands at higher elevations. Brown bears, lynx, and wild boar inhabit the forests, with brown bear populations estimated at approximately 60 individuals in a 2015 survey. The region contains more than 1,000 plant species according to botanical surveys conducted by the Research Institute of Forests and Rangelands. Sabalan volcano and its surrounding protected zones include alpine meadows above 3,000 meters and crater lakes formed in the summit caldera.