Boulby Quarries is a 40.3 hectare geological Site of Special Scientific Interest in Redcar and Cleveland, North Yorkshire, England notified in 1989. It is located close to the coast and the village of Boulby.
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.
Langbaurgh Ridge is an 8.0 hectare geological Site of Special Scientific Interest near the hamlet of Langbaurgh in North Yorkshire, England, notified in 1986. The site crosses the boundary of the Redcar and Cleveland district and Hambleton District.
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.
Hart Bog is a 1.79 hectare biological Site of Special Scientific Interest in County Durham, England notified in 1968.
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 in North Yorkshire, England notified in 1999.
Whitton Bridge Pasture is a Site of Special Scientific Interest (SSSI) in the unitary authority of Stockton-on-Tees, England. At 3.18 hectares (7.9 acres) it lies to the south of Whitton village and north west of Stockton-on-Tees. SSSIs are chosen by Natural England, and Whitton Bridge Pasture was designated in 2004 because of its biological interest. It is one of 18 SSSIs in the Cleveland area of search.
Saltburn Gill is an 18.9 hectare biological Site of Special Scientific Interest in Redcar and Cleveland district, in the ceremonial county of North Yorkshire, England notified in 1986.
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.
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 biological Site of Special Scientific Interest in County Durham, England notified in 1997.
