Cyclone Sidr hits Bangladesh, killing an estimated 5,000 people and destroying parts of the world's largest mangrove forest, the Sundarbans.

Extremely Severe Cyclonic Storm Sidr was a tropical cyclone that resulted in one of the worst natural disasters in Bangladesh. The fourth named and the deadliest storm of the 2007 North Indian Ocean cyclone season, Sidr formed in the central Bay of Bengal, and quickly strengthened to reach peak 1-minute sustained winds of 260 km/h (160 mph), making it a Category-5 equivalent tropical cyclone on the Saffir–Simpson scale. The storm eventually made landfall in Bangladesh on November 15, 2007, leading to large-scale evacuations. At least 3,447 deaths have been blamed on the storm, with some estimates reaching 15,000.

Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world and among the most densely populated with a population of over 171 million within an area of 148,460 square kilometres (57,320 sq mi). Bangladesh shares land borders with India to the north, west, and east, and Myanmar to the southeast. It has a coastline along the Bay of Bengal to its south and is separated from Bhutan and Nepal by the Siliguri Corridor, and from China by the Indian state of Sikkim to its north. Dhaka, the capital and largest city, is the nation's political, financial, and cultural centre. Chittagong is the second-largest city and the busiest port of the country.

A mangrove is a shrub or tree that grows mainly in coastal saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen and remove salt, allowing them to tolerate conditions that kill most plants. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse due to convergent evolution in several plant families. They occur worldwide in the tropics and subtropics and even some temperate coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs and became widely distributed in part due to the movement of tectonic plates. The oldest known fossils of mangrove palm date to 75 million years ago.