Crystal River is a good base for exploring the Nature Coast, and several worthwhile destinations are within an easy drive.
Homosassa Springs Wildlife State Park is 12 miles south on US-19. The park's main feature is a natural spring where manatees gather year-round — unlike Crystal River, where manatee presence is seasonal, Homosassa has a permanent resident population cared for at the refuge. There's also a full complement of Florida wildlife including black bears, Florida panthers, and a large population of wading birds. The park's "Fish Bowl" underwater observatory lets you watch fish and manatees from below the waterline. About 30 minutes' drive.
Weeki Wachee Springs State Park is 40 miles south. Famous since 1947 for its "mermaid shows" performed by swimmers in the spring vent, Weeki Wachee also has a river boat ride through cypress swamp and a water park. The spring itself, one of the largest in Florida, is worth the visit on its own terms. About 45 minutes' drive.
Cedar Key, 50 miles north, is a small island town at the end of a causeway — one of the most atmospheric fishing villages left on the Gulf Coast. Famous for locally farmed clams, a small but good history museum, and a collection of weathered waterfront seafood restaurants. The Cedar Keys National Wildlife Refuge protects a string of islands just offshore; kayak rentals are available. About one hour north on US-19 then west on SR-24.
Gainesville is 60 miles east. Home to the University of Florida and the Florida Museum of Natural History, which houses the largest collection of natural history specimens in the Southeast, including a complete fossil record of Florida's prehistoric fauna. The Butterfly Rainforest, an enclosed walk-through garden with hundreds of live tropical butterflies, is a standout. About 75 minutes' drive via SR-44 and I-75.