 The Shimla to Spiti route is advised for travelers coming from lower altitudes as it gives them enough time to get acclimatized to the high altitude.This is because the road runs parallel to the Sutlej river initially, climbing steadily to at the confluence of the Spiti and Satluj near Khab.From Khab, the road runs along the Spiti River, climbing steeply up to Nako (elev. )