The Thames Middle is a designated transitional water body within the tidal Thames Estuary, classified as heavily modified. It is a significant saltwater and brackish environment stretching from Cremorne Gardens in London downstream to Stanford-le-Hope in Thurrock. This section of the estuary is characterized by its tidal regime, mixing freshwater flow with marine influences, and features large areas of maritime saltmarsh along its foreshore. The water body is managed under the Water Framework Directive and supports a diverse, estuarine fish community.