The Mekong Delta (Vietnamese: Đồng bằng Sông Cửu Long "Nine Dragon river delta") is the region in southwestern Vietnam where the Mekong River approaches and empties into the sea through a network of distributaries. The Mekong delta region encompasses a large portion of southwestern Vietnam of 39,000 square kilometres (15,000 sq mi). The size of the area covered by water depends on the season. The Mekong Delta has recently been dubbed as a "biological treasure trove". Over 10,000 new species have been discovered in previously unexplored areas of Mekong Delta, including a species of rat thought to be extinct.
The Mekong Delta, as a region, lies immediately to the west of Ho Chi Minh City, roughly forming a triangle stretching from Mỹ Tho in the east to Châu Đốc and Hà Tiên in the Northwest, down to Cà Mau and the South China Sea at the southernmost tip of Vietnam, and including the island of Phú Quốc.
The Mekong Delta region of Vietnam displays a variety of physical landscapes, but is dominated by flat flood plains in the south, with a few hills in the north and west. This diversity of terrain was largely the product of tectonic uplift and folding brought about by the collision of the Indian and Eurasian tectonic plates about 50 million years ago. The soil of the lower Delta consists mainly of sediment from the Mekong and its tributaries, deposited over thousands of years as the river changed its course due to the flatness of the low-lying terrain.
The Mekong Delta is the region with the smallest forest area in Vietnam. 300,000ha or 7.7% of the total area are forested as of 2011. The only provinces with large forests are Cà Mau Province and Kiên Giang Province, together accounting for two thirds of the region's forest area, while forests cover less than 5% of the area of all of the other eight provinces and cities.