Only a few kilometres northwest of the Parque Nacional de Doñana, the Paraje Natural de las Marismas del Odiel (Las Marismas de Odiel Natural Area) is a totally different environment; a tidal estuary with creeks, lagoons and salt marshes. The flora and to some extent the fauna is very different to that found in its larger neighbour.
The reserve is a collection of smaller protected areas, the Reserva Natural Marismas del Burro between Gibraleón and Huelva city; the Reserva Natural Isla de Enmedio between Aljaraque and Punta Umbría; the Paraje Natural Estero de Domingo Rubio south of La Rábida; and the Paraje Natural Lagunas de Palos y las Madres between Huelva and Mazagón.
The Las Marismas de Odiel Natural Area is considered the most important complex of tidal marshes in the Iberian Peninsula.