This is quite a long walk, nearly all in the forest, but with spectacular views at the beginning, middle, and end. The forest is a maze of paths, and because of recent storms and deteriorating markation it is easy to lose your way. Having a GPS navigation device would be advisable especially in bad weather [although for some strange reason the path at the start is not shown on some versions of Google maps>. A good place to park is at a free public car park on the left after you cross the bridge over the Sora on the road from Skofja Loka to Pustal [there is also a smaller parking area just a little further along the road at the bus stop on the left>. If you choose to do the ascent from Hrastnica [see below> you could drive to where the path starts in Hrastnica, saving about 1.5km of walking and ~100m of climbing. This path is not signposted but it is the cart-track that begins near house 163.
The direct ascent from Pustal begins at a signpost about 100m further along the road from the above mentioned parking areas, which directs you up a rough road [a Kalvarija> towards the church at Pustal [which is worth visiting as a detour and for the views of Skofja Loka>. The signpost says 2h to Osolnik but this assumes you walk briskly and continuously and do not have any problems finding the way! Unfortunately, the markation and path-finding problems begin almost immediately, the start of the path to Osolnik being easily missed. It begins at the 7th station of the cross, and is indicated by a now rusty sign post that is in the wrong place, several metres further up the Kalvarija. The path descends a few metres to a dry stream, then ascends steeply up the hill, running SE along a fence that borders a pasture. At various positions along this path there are excellent views over Skofja Loka and to the Kamniske Alpe [even better views can be obtained from the field on the other side of the pasture if you have the energy and time to climb it>.
After ~200m the path enters the forest, bends to the S, and after another ~300m of steep climbing reaches the top of the hill Sten [20min/489m>. The path then continues S roughly level along the crest of a ridge for ~1km before ascending again to the top of Mrtancova Planina [45min/545m>. It then descends to the SE before switching S and continuing to descend to a col ~1km S of Mrtancova Planina [55min>. THIS IS THE MOST CRITICAL POINT IN THE WALK AS MANY PATHS MEET HERE AND IT IS NOT CLEAR WHICH TO FOLLOW. [One descends steeply W to Hrastnica, and is a good alternative route to or from Pustal>. The path to Osolnik is actually invisible, being up a step just to the right of a tree marked E7 in red letters. It then climbs SSE directly up to Vrh Rebra [75min/682m>, one of the most scenic open pastures in Slovenia with spectacular views of Kranj and the Kamniske Alpe to the NE, and Skofja Loka and the mountains to the NW, including Triglav on a clear day.
Follow the winding cart-track up through the pasture to a war memorial. Here you have two choices. If you take the path to the left, keep right after ~100m where the path branches, then keep left as the path enters a channel, and after ~500m you meet a road where you should turn right. The path on the right of the war memorial follows a road past a farm before ascending the hill. Both paths from the war memorial converge after ~1km at a crossroads where there are large wood piles and a large wood shed. Here again you have two choices. A path behind the large wood shed climbs steeply through the forest. When the path splits after ~100m keep left, and do the same at each subsequent junction, and you will reach the top of Osolnik where the well preserved church overlooks large open meadows with extensive views to the E, S, and W [857m/40min from Vrh Rebra>. The road to the left that heads off SE is an easier and much more scenic but much longer route to the top.
When returning it is best to use the alternate routes to the ones you took during the ascent. If you choose to begin your descent on the road, the steep meadow that descends E towards Kamniske Alpe between trees provides a shortcut that saves almost 1km of walking. When you get to the large woodshed, the two alternatives are a road heading downhill NW to the farm, or a road that runs initially level in a more N direction. Both bring you to the meadow at Vrh Rubra. If you did not ascend Osolnik via this route you will have a major problem locating the path from the meadow down to Skofja Loka. The best way is to follow the cart track as it zig-zags down the meadow. The last section runs next to a fence at the top of the forest and just before the cart-track ends at the corner of the forest turn sharp right along the fence where you should see a fence post with a yellow arrow. Follow the fence ~100m downhill then as it begins to climb again you will see the path to Skofja Loka marked with a signpost.
When you get to the tree marked E7 you have two choices, the rather longer up and down path through the forest to Pustal, with the benefit of excellent views at the end, or the route down to Hrastnica and then along the road to Pustal, the main advantages being no more climbing and saving ~1.5km of walking if you parked the car at Hrastnica.
A map of the various paths described above can be viewed at:
http://www.everytrail.com/view_trip.php?trip_id=2873444