The Cochamó Valley is known as the Yosemite of South America. Puelo Patagonia

A wealthy businessman has agreed to sell a vast swath of Chile’s wilderness for $63 million. The buyers: a band of activists who have spent years thwarting his efforts to develop the property. They have two years to raise the necessary funds.

The deal is a case study in modern-day conservation. It took a unique confluence of legal, financial and political resources — plus a bit of luck — to protect the lands from relentless development.