A narrow mountain pass, not very pronounced,between scrub-overed mountainside of the Col Mughi and the northern shoulder of the Creton dell'Arco from which the pass takes its name. The name already gives the game away!. There really is an arch! An unusual form of erosion, the result of millennia of activity by atmospheric agents, which carved this great rock arch. The pass connects the area of the Siera-Cadin Vette Nere with the Cadin di Fuori.
The proposed route is in full sun, not tiring and very fulfilling because, although the altitude is not that great, you almost get the impression of being on a mountaintop, so wide and beautiful is the panorama in almost all directions up there. A tip: given the narrowness of the site, in the presence of several walkers (a not uncommon event), rather than stopping at the pass and perhaps even being forced to eat a sandwich standing, it’s worth moving ten metres to the right (north) towards the Col dei Mughi, where you'll find a bit more space for a little well-deserved break.
Follow itinerary n. 6 as far as the fork at 1518 m (signed) from whence a path (n. 317) sets off down towards the riverbed of the newly-sprung river Siera, crossing it using a comfortable boardwalk before heading into the forest and rising with wide, smooth and regular turns. Almost without realizing it you find yourself out of the larch and fir and in a dominant position overlooking the open spaces surrounding the Siera pass below. A few more comfortable turns and you reach your destination.
The return takes place along the path used for the ascent.
A good alternative is to return to Sappada using itinerary n. 8 (note: this includes a short section with difficulty EE) thus completing the ring of the Col Mughi.