The river rises near the town of Honsfeld in the municipality of Büllingen, at about 600 meters above sea level. The basin is located in the High Ardennes, the highest region of Belgium. At 674 metres, Baraque Michel is one of the highest points in Belgium and forms part of the watershed of the Amblève basin. The mouth of the Amblève (in the Ourthe, which in turn flows into the Meuse) near Comblain-au-Pont, on the other hand, is only 120 meters high. As a result, the Amblève has a high drop.
The valley of the Amblève is especially narrow. Near the village of Cheneux, the river is relatively wide and then suddenly narrows along the narrow Hé des Zeftais. Railway line 42, which follows the valley from Trois-Ponts, passes through two tunnels here: those of Cheneux (250 m) and Xhierfomont (127 m). A little further on, the river flows more than four kilometers to the north. Here, at Fonds de Quarreux, the valley is narrowest.
The valley of the Amblève is seen as one of the most beautiful areas in the High Ardennes and is partly European protected as a Natura 2000 area (Vallée de l'Amblève du Pont de Targnon à Remouchamps, Basse Vallée de l'Amblève,... ).