Picos, Brazil

With a population of 83,090, Picos is no quaint mountain hamlet. The harsh reality is that this remote outpost in the Amazon basin is a logistical nightmare for would-be residents. Access is severely restricted, requiring special permits and accredited guides just to reach the trailhead - a four-day jungle trek in itself. And once there, visitors face the ever-present threat of river blindness, malaria, and yellow fever. While local gold panners may offer a friendly face, their presence is technically illegal, underscoring the bureaucratic headaches that come with living in this isolated, guarded national park. Picos is for the hardiest of adventurers only.