The Krekengebied (creek area) near Ouwerkerk is a nature reserve of about 140 hectares. After the 1953 flood, water flowed into the land here for a long time. The breach in the dike at Ouwerkerk was the last to be closed, in November 1953. The salt made the soil unsuitable for farming. Woodland took its place, with oaks, poplars, ash, elms and beeches.
Songbirds such as the chiffchaff and willow warbler breed here. You may also see kingfishers, swans, woodpeckers, grebes and birds of prey, and in winter, with luck, a peregrine falcon. In the inlet between the sea dike and the large creek along Weg van de Buitenlandse Pers, coastal birds breed and salt-tolerant plants such as samphire and sea aster grow.