Unimpressed with it, she called the Miami River about "an inch long",[30] but in researching it became more interested in the Everglades and persuaded the publisher instead to allow her to write about them. She spent five years researching what little scientific knowledge was recorded about the ecology and history of the Everglades and South Florida. Douglas spent time with geologist Garald Parker, who discovered that all of South Florida's fresh water source was the Biscayne Aquifer, and it was filled by the Everglades.