Oh my gosh! It IS a magic Northward flowing river!
"The St. Johns is the longest river in Florida - 310 miles long. It is one of the few rivers in the United States that flows north. The source of the river, or headwaters, is a large marshy area in Indian River County that flows north and turns eastward at Jacksonville to its mouth in the Atlantic Ocean."
https://www.google.com/url?sa=...
"The total drop of the river from its source in swamps south of Melbourne to its mouth in the Atlantic near Jacksonville is less than 30 feet, or about one inch per mile, making it one of the "laziest" rivers in the world."
https://www.google.com/url?sa=...
One of the laziest rivers in the world!
So basically, it's dangerously close to being a lagoon, or a lake.