Borasu Pass or Bara-su is a high mountain pass in the Himalaya Mountains of Uttarakhand in the India. The pass is located on the border of Uttarakhand and Himachal Pradesh near the border with Tibet. It was an ancient trade route between Har Ki Doon valley and Kinnaur valley.

Situated at an elevation of 5480 meters, Borasu is a high altitude pass that bisects the border between Uttarakhand and Himachal Pradesh. It is the pass that connected Tons valley in Uttarakhand to Baspa river valley.
 It is believed to be an ancient trade route between the two valleys. The Borasu Pass offers varied landscapes that leave treks and travelers awestruck. It is one of the rarely explored regions in the Himalayas that is worth a mention.

Climate

In summer, temperatures range from 0 °C (32 °F) to more lower. After November, the temperature falls down to several degree lower from 0 °C (32 °F). Precipitation in Baspa Valley is low in scale. Comparatively in the side of Tons valley rainfall is often common. Generally, snowfall is received after October.