Dique San Juan Carlos I Road. This long dike road runs along the center of the esturary and is a great way to see the marshland, with views to the Odiel river on one side the Gulf of Cádiz on the other. The road goes for ~20 km, starting from just over the Sobre el rio de Aljaraque Bridge. The Anastasio Senra Visitor Center is located 2 km from the bridge, and has restrooms and trail information. Most of the road, which is a hard concrete surface, has no shoulder, but there’s very light traffic. Note: very exposed, use caution in heat.
Bike Path Near Aljaraque Bridge. 8 km out and back. From the same bridge that accesses the Dique San Juan Carlos I Road, a paved bike path runs for 4km along the estuary, with great views. This is a great 5 mile out and back. For a longer run, the path continues for 9 km south to Playa La Bota (beach), paralleling the A-497 road (not that scenic). ROUTE MAP
Trails Near Visitor Center. There are several trails near the Anastasio Senra Visitor Center that are lovely for running. From the visitor center, take the gravel trail to the Observatorio de Aves (bird watching spot). You can keep going for several km. We recommend obtaining a map/info at the Visitor Center.
Via Verde de Littoral. This is a paved, signposted path along a former railway line that runs for 49 km between Ayamonte and Gibraleón. Lots of great water and marshland views and a good opportunity for a longer run. The section of the path near the Marismas del Odiel is at the northern end, near Gibraleón (footbridge crossing the river). Detailed route directions here.