Titchwell Marsh is an English nature reserve owned and managed by the Royal Society for the Protection of Birds (RSPB). Located on the north coast of the county of Norfolk, between the villages of Titchwell and Thornham, about 8 km (5.0 mi) east of the seaside resort of Hunstanton, its 171 hectares (420 acres) include reed beds, saltmarshes, a freshwater lagoon and sandy beach, with a small woodland area near the car park. This internationally important reserve is part of the North Norfolk Coast Site of Special Scientific Interest (SSSI) and the Norfolk Coast Area of Outstanding Natural Beauty (AONB), and is also protected through Natura 2000, Special Protection Area (SPA) and Ramsar listings.
The reserve is important for some scarce breeding birds, such as pied avocets on the islands, and western marsh harriers, Eurasian bitterns and bearded reedlings in the reeds. To encourage bitterns to breed, the reed beds have been improved to make them wetter, and the lagoon has been stocked with the common rudd. Typical wetland birds such as the water rail, reed warbler and sedge warbler also appear, and little egrets are common. The reserve has regularly attracted rarities, as its location is important for migrating birds. Ducks and geese winter at Titchwell in considerable numbers, and the reserve shelters the endangered European water vole.
Facilities include three bird hides, a seawatching platform, two nature trails, and a visitor centre. Because of concerns about climate change, a major project in 2010 and 2011 brought improvements to the banks around the freshwater lagoon and the conversion of the brackish lagoon to tidal saltmarsh, a more effective barrier to encroachment by the sea.
Titchwell Marsh is archaeologically significant, with artefacts dating back to the Upper Paleolithic, and has remains of military constructions from both world wars. These include brickwork from a First World War military hospital and 1940s artillery targets for armoured fighting vehicles and warplanes in the Second World War.