One of the "hard things" I've come across was turn of the century explorations. The stories of polar explorers like Ernest Shackleton (chronicled in Lansing's Endurance) or tropical ones like "River of Doubt" detailing Roosevelt's exploration of the Amazon tributary are fascinating stories of how people's grit accomplished hard things.
i understand polar expeditions, but werent people already living in amazon
There were tribals in the area but it wasn't mapped.