Hartlepool Submerged Forest is a 19.7 hectare geological Site of Special Scientific Interest in County Durham, England notified in 1988. The site is located to the south of Hartlepool Docks.
Briarcroft Pasture is a 1.76 hectare biological Site of Special Scientific Interest in County Durham, England notified in 2004.
Cowpen Marsh is a 116.8 hectare biological Site of Special Scientific Interest in County Durham, England, notified in 1966. SSSIs are designated by Natural England, formally English Nature, which uses the 1974–1996 county system. This means there is no grouping of SSSIs by Stockton-on-Tees unitary authority, or County Durham which is the relevant ceremonial county. As such Cowpen Marsh is one of 18 SSSIs in the Cleveland area of search.
Seal Sands is a 294.37 hectare biological Site of Special Scientific Interest in County Durham, England, notified in 1966.
Lovell Hill Pools is a 9.2 hectare biological Site of Special Scientific Interest (SSSI) in North Yorkshire, England notified in 1999.
Seaton Dunes and Common is a 312.1 hectare biological Site of Special Scientific Interest in Hartlepool, County Durham, England notified in 1966. Part of it is a Local Nature Reserve.
Pinkney And Gerrick Woods is a 62.7 hectare biological Site of Special Scientific Interest in North Yorkshire, England notified in 1954.
Redcar Rocks is a 31.1 hectare biological and geological Site of Special Scientific Interest in North Yorkshire, England notified in 1984.
South Gare & Coatham Sands SSSI is a 381.2 hectare biological Site of Special Scientific Interest in North Yorkshire, England notified in 1971.
Tees and Hartlepool Foreshore and Wetlands SSSI is a 255.62-hectare (631.7-acre) biological Site of Special Scientific Interest in County Durham, England notified in 1997.
Waldridge Fell is a Site of Special Scientific Interest located immediately south-west of Chester-le-Street in the northern part of County Durham, England. It is one of the largest areas of lowland heath in County Durham and contains the only lowland valley-mire in the county. The fell is home to a number of plants and insects that are scarce to rare elsewhere in the county.
