Lake Lillian is a 36acre freshwater lake in northern Highlands County, Florida. It is adjacent to the Avon Park Lakes Subdivision, north of the city of Avon Park. The slope of the lake drops quickly from the shoreline to a depth of about 45ft.This lake has no public access, as it is entirely surrounded by private property. On the northeast side is the now vacant Walker Memorial Hospital. On the southwest side is the local Seventh-day Adventist Church.