Head westwards from the Ecuadorian coast, over the snow-topped Andes and mountain plateaus, and deep into the misty rainforests that cascade down to the Amazon Basin. That's where you'll find the vast reserves of Yasuni National Park, cut off from most cities and towns, and linked to the known world only via the winding Rio Napo. A visit here is a visit right into the heart of the South American wilds, where rare reptiles cohabit in the undergrowth, wooly monkeys bob on the boughs, multicolored frogs croak on the bark, and panthers stalk the woods. The sheer wealth of life here has led conservationists to hail Yasuni as an international biosphere reserve. That's brought both eco warriors and Yasuni National Park tour guides offering excursions deep into the untrodden forests. However, Yasuni is also famed for something else: Oil. It's thought that large proportions of Ecuador's reserves lie trapped under the ground here, which has made the whole place a flashpoint on the frontline of environmentalism. As of 2016, the government confirmed that drilling had begun.