Silver Glen Springs is a first-magnitude spring located in Ocala National Forest, between the unincorporated communities of Salt Springs and Astor, Fla. The spring emerges from one of the largest and longest underwater cave complexes in the St. Johns River basin, and flows down a 0.6-mile spring run to Lake George along the St. Johns River. Evidence of human use at Silver Glen Springs dates back at least 7,000 years, and includes the remains of two massive shell mounds built atop mortuaries near the spring pool and the mouth of the spring run at Lake George. The spring is a popular destination for swimming, boating, fishing, wildlife viewing and viewing the spring.