The lower Ruvuma river is formed by the junction at of two branches of nearly equal importance, the longer of which, the
Lujenda, comes from the south-west, the other, which still bears the name Ruvuma, from the west. Its source lies on an undulating plateau, high, immediately to the east of
Lake Nyasa, at , the head-stream flowing first due west before turning south and east. In its eastward course, the Ruvuma flows near the base of the escarpment of an arid
sandstone plateau to the north, from which direction the streams, which have cut themselves deep channels in the plateau edge, have almost all short courses. On the opposite bank the Ruvuma receives, besides the Lujenda, the
Msinje River and
Luchulingo River, flowing in broad valleys running from south to north. The Lujenda rises in proximity to
Lake Chilwa, in the small
Lake Chiuta (), the
swamps to the south of this being separated from Chilwa only by a narrow wooded ridge. The stream which issues from Chiuta passes by a swampy valley into the narrow Lake Amaramba, from which the Lujenda River finally issues as a stream wide. Lower down it varies greatly in breadth, containing in many parts long wooded
islands which rise above the flood level, and are often inhabited. The river is fordable in many places in the
dry season. At its mouth it is about wide. The lower Ruvuma, which is often wide but generally shallow, flows through a swampy valley flanked by plateau escarpments containing several small
backwaters of the river. The mouth is near , the boundary near the coast being formed by the parallel of . The length of the Ruvuma is about . == Bridge ==