Just before the Umba flows into the Indian Ocean , it crosses the border to Kenya .
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 , Mbalamu River crosses the border to Kenya .
At Lelwa it empties the Mbalamu River , which comes from the extreme north of the Usambara Mountains , and the Mglumi River into the Umba .