She wrote a book, first published in 1947, called The Everglades: River of Grass. I was urged to read the book. I found a copy at my University's library and read it. I later picked up a revised edition (1987) with an afterward, from the Everglades National Park Service.
The Friends of the Everglades was founded by Marjory Stoneman Douglas, you might want to check out their bio of her here. Their mission is to protect and restore the Everglades.
At the time I did my research, I had never been to the Everglades. In reading her book, especially her first chapter, the Everglades came alive to me. She had the gift of painting a wonderful visual picture of the 'Glades. Her first sentence is poignant:
There are no other Everglades in the world. They are, they have always been, one of the unique regions of the earth, never wholly known. (Stoneham Douglas, 1987, p.5)
I felt her sadness as she told of the destruction of large portions of her beloved 'Glades. It was her advocacy on behalf of the 'Glades that was, in large measure, responsible for the establishment of the Everglades National Park in 1947. She died at the age of 108 in the late 1998.