The reason for this is Blue Spring’s year-round appeal. The park is sustained by tourists and nature lovers who come from miles around to get a glimpse of what Florida may have looked like years ago. During the hot summer and fall months, tourists enjoy swimming in the spring’s refreshing 72.5 degree water. During the late fall and winter months, the park is transformed into a refuge for manatees. The manatees are drawn to the spring’s comparatively warmer water when river temperatures fall below 68 degrees. The manatees, in turn, draw in a large number of tourists. In fact, due to the extraordinary amount of visitors during the manatee season, the park often reaches capacity by mid morning and remains at capacity until late afternoon. Spring breakers enjoy the park as well. Some catch the tail end of manatee season, and others enjoy the first taste of summer swimming during the later months of spring. 
Other attractions at the park include boat cruises and tours on the St. John’s River, cabins, camping, canoeing and kayaking, a concession area and a restaurant, hiking and a nature trail, an interpretive exhibit, picnicking, swimming, snorkeling, scuba diving, fishing, and wildlife viewing. The historical aspect of Blue Spring is also interesting to many guests (see History page for more details). St. Johns Boat Tour: The St. John’s River boat tour is a two hour nature and ecological cruise which explores the historic and scenic aspects of “Real Florida.” More information can be found at St. Johns River Cruises.
Cabins: Well-equipped cabins are also available on locations very near to the spring. Camping: Blue Spring has 51 campsites which are located in the sand pine scrub and are within walking distance of the spring. Blue Spring State Park also offers the Bedtime Story Camper Lending Library of picture books for campers aged four to nine.
Canoeing and Kayaking: The spring’s crystal clear water is an attractive location for canoeing and kayaking. The spring and spring run are closed during manatee season, however.
Concessions and Restaurant: For the convenience of the visitors who do not wish to picnic, concessions and a restaurant are located within the park.
Hiking/Nature Trail: The spring boasts of pristine beauty which dates back to the time of Florida’s earliest settlers. Visitors are welcome to self-guided enjoy hiking trails during their stay.
Picnicking: The park also has two different picnic areas complete with covered pavilions and grills.
Swimming: Blue Spring attracts many swimmers and scuba divers who are drawn to the cool, clear water.
Wildlife Viewing: In addition to being a manatee refuge, it harbors a vast array of birds, fish, reptiles, and other interesting plants and animals that visitors to enjoy viewing.
More info can be found at the Florida State Parks website
Enger, Eldon, and Bradley Smith. Environmental Science. 11th. New York, NY: McGraw-Hill, 2008. 488. Print.