West Thurrock Lagoon and Marshes is a 66.1-hectare (163-acre) biological Site of Special Scientific Interest in West Thurrock in Essex.

[1][2] The site is important for wintering waders and wildfowl which feed on the mudflats.

Reed warblers, sedge warblers and bearded tits breed on reed beds in the lagoon, and teals and grey herons roost on the shallow waters and grassy islands.

[1] The conservation charity Buglife fought to prevent development of the site, and succeeded in 2014.

[3] The Thames Estuary Path goes through West Thurrock Marshes.