Indian River Lagoon Preserve State Park, located on a barrier island south of Melbourne, is billed as the most biologically diverse estuary in North America. One can do a loop of ~6 miles on trails around the park’s mangrove wetlands and salt marshes. Thanks to Richard Magin for the recommendation & description.
The route within the Indian River Lagoon Preserve State Park is mainly along the Indian River and other canals and small ponds, with several nice water views and small sand beaches. It is out and back from the parking lot with the turn-around at the ”locked’ back gate of Honest John’s Fish Camp. Unfortunately, you cannot traverse the fish camp. There is abundant wildlife in the air and on the water, including big gators in the canals. The terrain is flat, with morning and afternoon shade on packed sand access roads. There is bicycle and pedestrian access (some pets on leashes). Water & restrooms are available within a 1/4 of the trail head in the South Beach Community Center.
Add-Ons: The route can be extended north to the trails of the Maritime Hammock Sanctuary off A1A (with parking) or in the Melbourne Shores residential area (no parking).