"In many villages they began to realize that a simple swim in the river caused rashes, " said Ianukula Kaiabisuia, coordinator of Xingu Park.

CNN: STORY HIGHLIGHTS

Guyana is one of the last existing strongholds for these native South American animals, and visitors can even swim in the river with them.

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Following Aaron's death his family put two life rings at the weir with another one provided by the CRT, alongside a sign warning people not to swim in the river.

BBC: Aaron Burgess Saltford Weir death was accidental

Strel plans to swim across the Grand Canyon , along 1, 000 miles of the freezing Mackenzie River in Canada, and the length of the 2, 000-mile Volga .

BBC: What adventures are actually left?

After all, it is one that was introduced in the United States into the Mississippi River near Mississippi, and has managed to swim upstream all the way across our country to the point where that river meets up with the Illinois River.

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