Theodore Roosevelt’s River of Doubt expedition and giant-anaconda claims

Record summary

The Roosevelt-Rondon expedition traversed the Brazilian interior in 1913–1914 and generated later claims about unusually large anacondas and other remarkable animals. The expedition is a useful lead because its published narratives show how dangerous travel, second-hand testimony and natural-history expectations shaped reports of unknown creatures. The expedition itself documented real environmental and zoological observations, but alleged extreme snake sizes are not equivalent to evidence of a new species. Researchers should distinguish Roosevelt’s published narrative, Rondon’s records and later sensational retellings.