Climb back up the left-hand side and continue in the direction of Alpe Pertusio on a flat trail along the river, which on sunny days is coloured in wonderful pale blue hues with white sandy coves.

It is a very picturesque stretch of river: the river with its sinuous bends, one after the other, creates a unique riverbed, which generates a unique ecosystem after each flood.

In addition to the trout in the water, there are hundreds of species of insects such as mayflies, stoneflies and caddisflies. What is more, life does not stop at the visible parts: even in the sediment under the gravel several metres deep, it is possible to encounter tiny aquatic organisms.

Note immediately the signpost indicating the source of the Brenno River, which can be reached in a matter of minutes.

The spring is a truly marvellous spectacle: the water gushes out clear and pure directly from a crevice at the foot of the mountain. With a maximum flow rate of 1300 l/s, it is one of the largest in the canton: two divers managed to explore 300 metres of it, reaching a depth of 45 metres!

The trail then immediately ascends in a northerly direction, through a fairly steep, short passage to return to the starting point along the wide meadows of the Lucomagno Pass.