It´s a river, with low tide the water is like a mirrow if not choppy. The river goes into a bay, there are small waves if the wind direction is onshore.
AP-4 to Puerto Real, then 443 west towards Cadiz. After about 3 km after Puerto Real exit (first big exit after Puerto Real). Drive north (right). At the first roundabout take the third right (Northeast direction) and at the next roundabout take the first right, but don't drive along the paved road, thae the dirt road at the corner which leads you to the water.
)