John Augustine Zahm, Cândido Rondon, Kermit Roosevelt, Cherrie, Miller, four Brazilians, Roosevelt, Fiala. Only Roosevelt, Kermit, Cherrie, Rondon, and the Brazilians traveled down the River of Doubt.
Once in South America, a new, far more ambitious goal was added: to find the headwaters of the Rio da Duvida (Portuguese for "River of Doubt"), and trace it north to the Madeira and thence to the Amazon River. It was later renamed Roosevelt River in honor of the former president. Roosevelt's crew consisted of his son Kermit, Colonel Rondon, naturalist George Kruck Cherrie (sent by the American Museum of Natural History), Brazilian Lieutenant João Lira, team physician Dr. José Antonio Cajazeira, and 16 skilled paddlers and porters. Roosevelt also identified Leo Miller (another AMNH recommendation), Anthony Fiala, Frank Harper, and Jacob Sigg as crew members.[301] The initial expedition started somewhat tenuously on December 9, 1913, at the height of the rainy season. The trip down the River of Doubt started on February 27, 1914.[302]
During the trip down the river, Roosevelt suffered a minor leg wound after he jumped into the river to try to prevent two canoes from smashing against the rocks. 