Janela do Inferno is a 7.6-kilometre circuit from Remédios that turns former water-supply infrastructure into a landscape route. Casa da Água introduces the subject before the path crosses pasture, small woods and watercourses. Tunnels, aqueducts, channels and service buildings appear throughout the walk as components of a network built to move water across irregular relief.
After passing Ribeira Seca and a junction with PR42SMI, the route reaches Janela do Inferno. A spring emerges from a cavity in a vertical wall and feeds a small pool, creating a cool, shaded environment. Newts and other water-associated life underline the sensitivity of the place. Its dramatic name contrasts with the intimate scale of the setting, whose interest comes from geology, moisture and human engineering together.
The return branch follows the opposite bank, crosses aqueducts and includes a final tunnel around 50 metres long before re-entering agricultural ground. A Regional Road crossing and Remédios church complete the loop. Although rated easy and estimated at two and a half hours, it still requires a torch, grippy footwear and care around water. The walk explains supply as a territorial system rather than a collection of isolated structures.