Blue Spring is a first magnitude spring on the St. Johns River. Gold Rush prospector turned orange-grower Louis Thursby purchased Blue Spring in 1856. Before the railroad rolled through in the 1880s, Thursby's Blue Spring Landing was a hotbed of steamboat activity, shipping tourists and goods to Jacksonville and beyond. Mrs. Thursby was Orange City's first postmistress. 'The Forgotten Mermaids,'
an episode of the Underwater World of Jacques Cousteau, was filmed here in 1971. The documentary brought attention to the manatee and the importance of Blue Spring as a winter refuge, greatly influencing the state's decision to purchase the land.