What is the longest river in Vietnam?
Vietnam has 392 rivers, according to statistics from the Vietnam River Management Department (Cục quản lý đường sông Việt Nam). Some rivers originate in other countries and flow through Vietnamese territory, some originate in Vietnam and flow into other countries, and some originate in Vietnam and flow only within its borders before reaching the sea.
Today, we introduce the longest river in Vietnam by two criteria: the longest river originating in Vietnam, and the longest river flowing through Vietnamese territory.
The longest river originating in Vietnam
That is the Đồng Nai River.
The Đồng Nai River.
That's right: the Đồng Nai is Vietnam's longest domestic river and has the second-largest basin in southern Vietnam, after only the Cửu Long (Mekong). It flows through the former Lâm Đồng, Đắk Nông, Bình Phước, Đồng Nai and Bình Dương provinces and Ho Chi Minh City (since the July 2025 merger, today's Lâm Đồng and Đồng Nai provinces and Ho Chi Minh City), with a length of 586km (364 miles) and a basin of 38,600km² (14,910mi2).
The Đồng Nai River rises on the Lâm Viên Plateau in Lâm Đồng province in Vietnam's Central Highlands; its upper reaches are known as the Đắc Dung.
The Đồng Nai River empties into the East Sea in the Cần Giờ area of Ho Chi Minh City. Its main tributaries include the Đa Nhim, Bé, La Ngà, Sài Gòn, Đạ Hoai and Vàm Cỏ rivers. Its distributaries are called the Lòng Tàu (Ngã Bảy), Đồng Tranh, Thị Vải and Soài Rạp (Soi) rivers, among others.
The longest river flowing through Vietnam
That is the Mekong River.
The Mekong River.
The Mekong rises in the high mountains of Qinghai province, crosses Tibet and runs the full length of Yunnan province (China), then passes through Myanmar, Thailand, Laos and Cambodia before entering Vietnam.
It ranks 12th in the world by length (7th in Asia) and 10th by water discharge (annual flow of about 475 billion m³). Its average discharge is 13,200m³/s, and in the flood season it can reach 30,000m³/s. Its basin covers about 795,000km² (according to the Mekong River Commission) or more than 810,000km² (according to Encyclopaedia Britannica 2004).
Why is the Mekong called the Cửu Long River?
Because the Mekong reaches the sea through as many as nine mouths, it is called the Cửu Long, meaning "Nine Dragons."
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