A gruelling 2,077 mile challenge faces Cambridge academic Mark de Rond and rowing coach Anton Wright as they attempt to row the navigable length of the River Amazon.
Fast-moving debris, waterborne parasites and uninhabited jungle face the pair, who aim to be the first to cover the distance without support from back-up teams.
The biggest threat comes not from the natural environment, says Dr de Rond, but from hostage takers.
Swimmers, canoeists, even bathtub-paddlers have all risen to the challenge, but the Cambridge pair will enter the record books as the first 'unsupported' attempt.
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