In a remote lowland forest in northern Argentina, giant anteaters snuffle around termite mounds, and jaguars stalk prey along the muddy banks of the Bermejo River. Parque Nacional El Impenetrable, which opened in 2017, is one of the South American country’s newest and most diverse wildlife sanctuaries—and a growing site for ecotourism. Yet, these 320,000 acres of pristine wilderness were nearly lost to development following a brutal murder that gripped the nation.