The nonprofit started by former Patagonia executive Kris Tompkins and her late husband, The North Face co-founder Douglas Tompkins, has made what it says is the largest-ever land donation by a private entity to a country. Appearing with Chilean president Michelle Bachelet on March 16, Kris Tompkins announced that Tompkins Conservation plans to hand over more than 1 million acres (4,000 square km) to the nation of Chile.

In addition, the Chilean government agreed to designate or enhance protections on another 9 million acres (36,000 square km) of state land to conservation. The total conserved area is three times larger than the US’s Yosemite and Yellowstone National Parks combined.

The deal, which must still be finalized, would create five new national parks and expand three others—which will become part of a 17-park network stretching for 1,250 miles, or more than half the width of the United States. Tompkins Conservation says the wilderness areas will generate $270 million in ecotourism-related business annually, and employ more than 40,000.

Douglas Tompkins made his name founding two of the world’s most notable apparel brands, the outdoor equipment and clothing company The North Face and Esprit, the clothing company. With proceeds from the sale of Esprit in 1990 (he had sold his early share of The North Face for just $50,000), Tompkins left his businesses behind and moved to the tip of South America to pursue environmental conservation.

For the last two decades, Tompkins, along with his second wife, Kris—she is a former CEO of the Patagonia clothing company—sought to“rewild” South America’s ecosystems by reintroducing species and reversing biodiversity loss. The two concluded that large national parks were their best hope, and set about buying huge swathes of land, often home to degraded farms and ranches, to dedicate to conservation.

Reuters/Leo Beca An environmental activist up until the end.

The Tompkins’ holdings across South America’s rugged southern tip were so vast that critics accused them of plots to split the country in half or build an American nuclear waste site. But when developers planned to create a strong network of of dams and hydroelectric power lines in the country, the Tompkins’ project finally won Chilean public favor (although resistance from ranchers and industry persists). The Tompkins’ efforts, reports National Geographic, have protected more land (about 2.4 million acres) than those of any other private individual.

Douglas Tompkins died in 2015 at the age of 72. He had been kayaking on a lake in southern Chile when strong waves overturned his kayak. Several hours after his rescue, he died from severe hypothermia.