You boys ready for a real adventure? Come to the Azul mountains of Peru. Want to find a giant ground sloth? Lost city of gold? Perhaps an uncontacted tribe? Well this is where we will fricking find it. These mountains are have not been explored by anybody, not even the known native tribes in surrounding areas. Nobody has ever been here. Tarapoto is the nearest city. There is a cool lake called "lost world lagoon" which is probably the nearest spot that gets any human activity.
As you can see in the first image, it is a deep flat bowl completely surrounded by mountains.