The largest spring on the St Johns River, Blue Spring maintains a constant 72°F. Between November and March it becomes the winter refuge for up to 200 West Indian manatees. The best time to see them is before 11am; there's a wheelchair-accessible path to the viewing platform. This tranquil state park is a revitalizing spot to swim (prohibited when manatees are present), snorkel or canoe.
You can also spend two hours cruising the peaceful waters with St Johns River Cruises, whose nature tours offer a thoughtful insight into this fragile ecosystem.