Humans have hunted the Giant River Otter, contaminated its waterways, taken its food supplies and destroyed its nesting grounds. Today a new refuge for the world's largest otter faces a further ...

Waldemarin looks for the cream-colored markings on its neck that are as individual as a human’s fingerprints, but before she can make an identification, the giant otter ducks, dives and disappears.

“Ecotourism can be a doubleedged sword,” she tells me the day before we are to set out. “It can help conservation or disrupt it.” With a footprint that is often bigger than a human hand, the giant ...