The Rocca dell'Abisso

From Colle di Tenda (1871 m), the route follows the dirt road for Casterino (to the right, coming from Limone) as far as the hamlet of Colletta, where there is a crossroad with a former military service road leading to Fort Pernante and Fort Giaura.
The route follows a clear trail between the two roads and climbs steeply up the broad divide, through pastures and alders, climbing les steeply now, until it meets up again with the former military service road further uphill, which it had brushed up against twice before. Following the road uphill to the left, the route shortly arrives at Fort Pernante (previously Forte Pernante, 2114 m, 45 minutes from Colle di Tenda).
The trail leads down the western slope below the fort among alders, almost touching the old military road. It then leaves it abruptly to pass to the left of the rounded knoll of the Cime de Salaute, which the route passes to the right (north). With a flat traverse at mid slope, the trail rejoins the old military road at a hill beyond the Cime de Salaute, at which point the dirt road is reduced to a mule track. Proceeding to the left, it shortly reaches another small hill, the Bassa sovrana di Margheria (2079 m, 35 minutes from Fort Pernante).
Here, at a recently placed border marker, it meets the trail coming from Limonetto, on the right.
At the foot of the craggy slope of the Cima di Giaura, the trail passes by a path on the left that climbs up very steeply to the crest of the ridge, staying instead on the mule track that veers eastward and traverses, slightly uphill, on a rocky base. At the first switchback, to the left, the route leaves the old road (which, due to several landslides further uphill, is no longer passable even on foot) and follows the trail to the right, across a scree. The trail leads along the edge of a detritic hollow, through bushes, and passes just uphill of a miniscule lake without a name. After a long traverse, the trail crosses a small stream and reaches the eastern shore of Lake dell'Abisso (2207 m, 25 minutes from the Bassa sovrana di Margheria).
The trail then inverts its direction, proceeding uphill to the southeast until it rejoins the military road it came from, at the last switchback below the fort. With a challenging traverse along rocky cliff walls (attention to the brief tracts over landslides, quite exposed), the trail finally arrives at the grassy flat area on which stands the Fort de Giaure (formerly Forte Giaura, 2254 m, 15 minutes from Lake dell'Abisso).
Passing by the turnoff for the Lacs de PeÔrefique, the route climbs uphill on an old mule track with numerous switchbacks, along the steep grassy slope of Pra Giordano (there is a single shortcut to the left of the switchbacks, which avoids them all).
After the switchbacks, the climb continues fairly straight, still on the grassy slope. After passing by a turnoff on the right, the trail traverses northwest for an extended tract. As the altitude increases, the trail begins to lead through detritus and rubble: when it arrives at the foot of the last detritic slope, it rises in tight turns and then, leading to the left, it leads to the lower peak of the Rocca dell'Abisso (2755 m, 1 hour and 35 minutes from Fort de Giaure), where there is a cross and a weather station.
The primary peak, which is at almost the same altitude, is just a few meters away, but can only be reached by a risky climb along the crest.