The Mekong Delta (Vietnamese: ong bang Song Cuu Long, "Nine Dragon river delta" or simply Vietnamese: ong Bang Song Me Kong, "Mekong river delta"), also known as the Western Region (Vietnamese: Mien Tay) or the South-western region (Vietnamese: Tay Nam Bo) 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 over 40,500 square kilometres (15,600 sq mi). The size of the area covered by water depends on the season. The region comprises 12 provinces: Long An, ong Thap, Tien Giang, An Giang, Ben Tre, Vinh Long, Tra Vinh, Hau Giang, Kien Giang, Soc Trang, Bac Lieu, and Ca Mau, along with the province-level municipality of Can Tho.

Based on this passage, where is the mekong river delta located in vietnam? Let's give stream of consciousness first:
The relevant sentence in the passage is: The Mekong Delta (Vietnamese: ong bang Song Cuu Long, "Nine Dragon river delta" or simply Vietnamese: ong Bang Song Me Kong, "Mekong river delta"), also known as the Western Region (Vietnamese: Mien Tay) or the South-western region (Vietnamese: Tay Nam Bo) is the region in southwestern Vietnam where the Mekong River approaches and empties into the sea through a network of distributaries.
So, the final answer is southwestern Vietnam.