The Aluoja cascades are in the village of Pühajõe in Toila municipality, in the Mägara creek, which flows into Pühajõe valley from the west. Aluoja is a unique slate valley with a variety of cascades, clefts and springs.
Moving downriver, its terraces are 1.4 m, 0.7 m, 1.9 m, 1.3 m and 0.5 m in height. They expose different layers of limestone dating to different eras – the three top terraces from one era and the bottom two from another. The valley deepens suddenly by up to 10 metres. In places, particularly near the third terrace, it resembles a canyon.