The Maze, Canyonlands National Park, UT
For those unfamiliar, Utah's Canyonlands National Park is spectacular. And the Maze is it's most challenging and remote offering, a Martian landscape of sculptured rock and dust. From the nearest ranger station it's a several hour drive by 4WD, and there are no sources of water or food anywhere inside – the Park Service suggest most of the just 2,000 visitors annually spend three days or more, and so must be fully self-sufficient. That's just getting to the beginning of the Maze. As its name suggests, navigating through is tricky, with plenty of dead-ends and the constant threat of extreme heat, falling rocks and the potential for flash floods as well. Amazingly to-date there have been no deaths yet.