Parque Nacional das Nascentes do Rio Parnaíba Piauí

Spanning four states, this massive park protects a key area of cerrado (savanna) landscape and is famed for its intelligent capuchin monkeys. It's also home to endangered hyacinth macaws and wild wolves. While not technically open to the public, travelers can visit with advance permission from the park authorities. It's obligatory to enter with a local guide; the park management has a list of recommended local experts.