29 August 2013 Last updated at 00:42 GMT
By William KremerBBC World Service
David Good’s parents come from different countries – hardly unusual in the US where he was raised. But the 25-year-old’s family is far from ordinary – while his father is American, his mother is a tribeswoman living in a remote part of the Amazon. Two decades after she left, David realised he had to find her.
After three days on the Orinoco River, David Good felt sick.
He had been eaten alive by the relentless biting gnats, he was tired and thirsty. The air was dank and humid. Fierce rays of sunlight bounced off the surface of the piranha-filled river as the 40-horsepower motor puttered and the launch pushed further upriver, deeper into the Amazon.
His stomach was a knot of apprehension – he had not slept the previous night at all.
He was not a natural traveller or explorer. The lawns and parks of eastern Pennsylvania were his habitat and this trip to the Venezuelan Amazon – in July 2011 – was his first outside the US since early childhood.
And yet – as everyone kept telling him – things were going well. Normally, travellers heading to the Orinoco headwaters had to stop at the Guajaribo Rapids, unload all their goods and haul them overland, before pulling the boats past the treacherous rocks by rope.