The Mekong crosses Yunnan Province, China, and forms the border between Myanmar (Burma) and Laos and most of the border between Laos and Thailand. It then flows across Cambodia and southern Vietnam into a rich delta before emptying into the East Sea. In the upper course are steep descents and swift rapids, but the river is navigable south of Louangphrabang in Laos.

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 southeastern Vietnam of 39,000 square kilometres (15,000 sq mi). The size of the area covered by water depends on the season.

The most renowned places in the Mekong Delta are Mỹ Tho and Caí Bè near Ho Chi Minh City, then, more to the heart of the region, Vĩnh Long, Sa Đéc, and Cần Thơ, from whence it is possible to reach the remotest confines of the delta, South towards the mangroves and the East Sea, North towards Châu Đốc, or West towards the island of Phú Quốc.

The region was originally ruled by the Khmer people. It later became Cochinchina and part of French Indochina as it was conquered by the French. Following independence from France, the Mekong delta became part of the country of South Vietnam and eventually the country of Vietnam.

The area is home to large numbers of rice fields. In 1997, in large part thanks to the Mekong Delta, Vietnam was the third largest exporter of rice globally after Thailand and India. In 1997, Vietnam was the world's second largest exporter of rice. Additionally, the region is home to large exports of basa fish, Tra catfish and shrimp, much of which is exported.

This region has recently been dubbed as a 'biological treasure trove'. Over 1,000 new species have been discovered in previously unexplored areas of Mekong Delta, including a species of rat thought to be extinct.