Bangladesh covers an area of 144,000 square kilometres (about two-thirds the size of Victoria). It is mostly flat alluvial plains, crisscrossed by three main river systems, Padma (the Ganges), Jamuna (the Brahmaputra) and Meghna flowing down from the Himalayas into the Bay of Bengal, making the largest delta in the world. The Chittagong Hills Tract in the south-east is the high region and includes the highest peak, Keokradong, at 1,200 metres.
Bangladesh has a tropical monsoon climate marked by three seasons: summer from March to June, a monsoon or rainy season from July to October and a dry winter from November to February. The climate is marked by high temperatures and high humidity. Massive cyclones originating in the Bay of Bengal occur frequently at the beginning of summer and at the end of the monsoon seasons, during March and April, and October and November.
Over 90% of the country is composed of alluvial plains, which are less than 10 metres above sea level, making it extremely prone to flooding. About 11% is covered by forest, consisting mainly of broadleaf, evergreen species in the hill regions and deciduous varieties, such as acacia and banyan in the drier plains.
The Sundarban, one of the world’s largest mangrove forests is a World Heritage Site, and is home to 260 bird species, the estuarine crocodile, the Indian python and the threatened Bengal tiger.
Black bears, elephants, langurs, gibbons, otters, mongooses, ox, bison and deer are commonly found. Bangladesh has more than 600 bird species including kingfishers and fishing eagles.
Bangladesh is one of the most densely populated countries in the world with 1,263 persons per square kilometre. About 28% of the population live in urban areas. The biggest cities are the capital Dhaka (15.391 million), Chittagong (4.816 million) and Khulna (1.636 million). Tribal groups live mainly in the hill areas.