After recovering, on September 27, they  set to work building five dug-out canoes (pirogues), assisted by the Nez Perce. 
The Rockies were now behind them, the Pacific in front. On October 7 they broke camp, and started down the Clearwater River for the Snake and the Columbia. 
 All of these westerly-flowing rivers are fast because they fall from mountains to ocean in a short distance. 
As a result, travel was quick, and the expedition reached the Snake River on October 10.