The Bay of Cádiz Natural Park occupies a big part of San Fernando's municipal district. It opens four paths with access to marshes, dunes and the old salt marshes, some of which date back to 1750. All courses are easy to complete and surround a high ecological value area. The Salina de Dolores Route (4.5 km, one hour and a half) offers a privileged view; the Río Arillo path (2.5km, 1hour) is among the limits between San Fernando and Cádiz. The course, marked by river Guadalete's estuary, will show you a salt marsh which was active until the eighties. The Salina de Tres Amigos (1.9km, 45 minutes) is the most winding course in the whole lot. Finally, the Punta del Boquerón path (2km, 45 minutes) begins at the final part of the Camposoto promenade. On one side, on a sandy soil, the Caño de Sancti Petri remains as one of the best preserved marshes in the Park; on the other, the beach; and in the interior, the dunes formed by wind action.