The Umba River is located in northeastern Tanzania in Tanga Region. It rises in Schageiuforest (Shagayu) in the West Usambara Mountains at 2,000 m altitude and flows on the north side of the mountain range to the east. At Lelwa it empties the Mbalamu River, which comes from the extreme north of the Usambara Mountains, and the Mglumi River into the Umba. Just before the Umba flows into the Indian Ocean, it cross the border to Kenya. The mouth itself marks the most eastern point on the border between Tanzania and Kenya, which they largely made in a straight line to the northwest towards Lake Victoria in the 19th Century. On the upper reaches of the river in the mid-1960s rich deposits of precious stones, including sapphires and Spessartine, were discovered.