The name Suthu refers to Basotho people who lived near the source of the river, but were attacked and displaced by the Swazis.

[2] The river rises near Amsterdam, Mpumalanga, South Africa, and flows easterly through Eswatini, where it enters the Lebombo Mountains.

It then meanders through the Mozambican coastal plain and empties into southern Maputo Bay, some 85 kilometres downstream.

[3] In Eswatini, the river is called the Great Usutu or Lusutfu and flows through the towns of Bhunya, Luyengo, Siphofaneni, and Big Bend.

From the origin to its mouth, in order, tributaries are the: Sihanahana, Bonnie Brook, Mpuluzi, Buhlungu, Umvenvane, Lusushwana, Sidvokodvo, Mkhondvo, Mhlamani, Mzimneni, Mzimphofu, Mhlathuzane, Mtsindzekwa, Nyetane, Funuane, and the Pongola Rivers.