Boats lie scattered on the soggy bottom of a bay at low tide, on the Praia dos Cavacos near OlhΓ£o. High tides regularly flood the bay and parts of it surroundings on the Ria Formosa, while dead low water can leave a lot of grounds exposed. Birds and fishermen alike profit from the sometimes over two metre difference between ebb and flood. And recreational boaters need to choose their moments wisely with the moon.