Park at the car park next to the Ristoro Pian di Gembro and join the trail that darts off to the right straight after the garage, where the cross-country ski track maker is stored. You start on a footpath, which then turns into a road and brings you out at the junction to Prosolone.
Keep right and go past a few mountain cabins – now you’re heading towards monte Borca. The road flattens for a stretch before some hairpins. Keep left at each junction and you’ll start your return towards Prena, a cleared plateau. There’s one natural viewpoint with spectacular views over the Orobic Alps before the final descent back down to Prosolone, where the circular walk ends.
If you’re embarking on the Prena winter walk, standard snowy winter walking equipment is recommended (snowshoes, poles, and crampons if necessary).