Penna di Sumbra is formed almost completely of marble and changes its physiognomy greatly depending on the observation point. The summit reaches 1769 meters.
The mountain extends in an east-west direction with a long rocky ridge which to the north, towards Vagli, is fairly sweet, fresh and wooded, while to the south
it descends precipitously with marble walls that exceed 500 meters.
From Vagli the mountain looks like a giant crouched with its head facing west.
You can easily climb to the top via the GT3 path that from Lake Vagli passes on the Cornicchia coast, to get to the Maestà del Tribio. From here, heading SW you will find path 145 (GT3b) which leads to the summit through the wooded east ridge.
The summit is very grassy and somewhat reminiscent of the Apennine hills, it is particularly panoramic over the entire Apuan chain.
If you want to make a ring route to Vagli Sotto from the summit, you can follow the equipped section of the Ferrata Malfatti.
Upon reaching Fiocca Pass, continue along path 144 for Mount Fiocca (1709m) and Sella Pass.
Continuing on path 31 and for the Arnetola Valley (GT3b) you arrive in Vagli Sopra and then in Vagli Sotto.