The Boiuna or large snake, is a myth Amazonian Amerindian origin, described as a huge snake can turn dark vessels. Can also mimic the shapes of vessels, attracting castaways to the river bottom. The British Colonel Percy Harrison Fawcett, explorer who made ​​seven expeditions in the Amazon from 1906 to 1925, reported seeing giant snakes, or their evidence. In one of his diaries, he noted in 1907: "We were quietly following the current lazy, not far from the confluence of the Rio Negro when almost under the bow of igara there appeared a triangular head and several feet of undulating body. Was a giant anaconda."