One such pass among the many passes that cross into Himachal from Uttarakhand is Borasu.Situated at an elevation of 5450 m or 17,880 ft is challenge for season trekkers too . It connects the Tons river valley with Baspa river valley. The pass is open only for a few months before monsoons and then post monsoon before the winter sets in. It is a high but practical traverse into the great Kinnaur Valley, takes 5 -6 days from Har Ki Dun valley to Ranikhanda further into the Baspa Valley. From Har- ki - Dun the trail heads north along the Maninda Gad popularly known as Morinda Tal. Beyond that the ascent eases to Rathadu campsite 4000 m with a distant view of mountains and thereon the path winds up for 5km through a flower strewn narrow valley offering you a breathtaking diversity of landscapes and the trek is the perfect blend of lush meadows, riot of flowers such as Geranium , Bistorta etc Moraine path finally reaching Sauni Beda camping grounds.A steep climb on the rocky patch from here brings to Lamjoonga makeshift campsite.
After Lamjoonga campsite with a glacier to further up, climb strenuously, beware of crevasses in post monsoon on the either side of pass for about 4 km to the pass, one will be surprised and awestruck to see Nilkamal flowers in full bloom on the rocky patches along the pass and descent along the 60 -70 deg rocky slopes reaching Zupke glacier.The route through boulders requires some careful footing and proper balance.Beware and watchful of rockfalls and boulders coming down and there on further down to the Baspa river bed. The loose rocks and rockfall pose a danger, avoid attempting the pass in bad weather, during post monsoon.Cross the river by a bridge and reach the and Doaria camping grounds. From Doaria the trek to Chitkul is very easy on the legs. This trek is one of the best ways to get a feel and experience the Himalayan culture of Garhwal region and Kinnaur region respectively.