Marismas do Alba, also known as Xunqueira de Alba, is Pontevedra's easiest escape into real wetland country. The marsh sits where the Rons meets the Lérez, close enough to the city for a short walk but with reeds, mudflats, salt-tolerant plants, and enough birdlife to make it feel like a small estuary reserve rather than a municipal park.
Come for a quiet hour rather than a grand set piece. The paths are good for walking or cycling, and the interest is in the slow details: herons in the shallows, tidal channels changing with the water level, and the abrupt contrast between Pontevedra's stone streets and this flat green fringe just beyond them.