<P> With an area of 1,648,000 square kilometres (636,000 sq mi), Iran ranks eighteenth in size among the countries of the world . Iran shares its northern borders with three post-Soviet states: Armenia, Azerbaijan, and Turkmenistan . These borders extend for more than 2,000 kilometres (1,200 mi), including nearly 650 kilometres (400 mi) of water along the southern shore of the Caspian Sea . Iran's western borders are with Turkey in the north and Iraq in the south, terminating at the Arvand Rud . </P> <P> The Persian Gulf and Gulf of Oman littorals form the entire 1,770 kilometres (1,100 mi) southern border . To the east lie Afghanistan on the north and Pakistan on the far south . Iran's diagonal distance from Azerbaijan in the northwest to Sistan and Baluchestan Province in the southeast is approximately 2,333 kilometres (1,450 mi). </P> <P> The topography of Iran consists of rugged, mountainous rims surrounding high interior basins . The main mountain chain is the Zagros Mountains, a series of parallel ridges interspersed with plains that bisect the country from northwest to southeast . Many peaks in the Zagros exceed 3,000 metres (9,843 ft) above sea level, and in the south - central region of the country there are at least five peaks that are over 4,000 metres (13,123 ft). </P> <P> As the Zagros continue into southeastern Iran, the average elevation of the peaks declines dramatically to under 1,500 metres (4,921 ft). Rimming the Caspian Sea littoral is another chain of mountains, the narrow but high Alborz Mountains . Volcanic Mount Damavand, 5,610 metres (18,406 ft), located in the center of the Alborz, is not only the country's highest peak but also the highest mountain on the Eurasian landmass west of the Hindu Kush . </P>

Mountains along iran's border with iraq and the persian gulf