List of the largest Sites of Special Scientific Interest in England

This is a list of the largest Sites of Special Scientific Interest in England in decreasing order of size. A lower threshold of 100 hectares or one square kilometre has been used.

Sites more than 10,000 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres The Wash Norfolk / Lincolnshire63,135.01972 North York Moors North Yorkshire / Cleveland44,087.71998 Humber Estuary East Riding of Yorkshire / Lincolnshire37,000.62004 Dark Peak Derbyshire / Greater Manchester / South Yorkshire / West Yorkshire31,852.91951 Morecambe Bay Cumbria / Lancashire30,287.51975 Upper Solway Flats and Marshes Cumbria / ?29,950.51988 The New Forest Hampshire / Wiltshire28,947.41959 South Pennine Moors West Yorkshire / Great Manchester / Lancashire / North Yorkshire20,938.11994 Salisbury Plain Wiltshire / Hampshire19,689.91975 Breckland Forest Norfolk / Suffolk18,078.72000 Severn Estuary Avon / Somerset + others15,950.01976 Upper Teesdale County Durham14,035.61951 Moorhouse and Cross Fell Cumbria / County Durham13,707.01990 Dee Estuary Cheshire / Clwyd13,679.71954 Breckland Farmland Norfolk / Suffolk13,335.72000 North Dartmoor Devon13,413.21952 North Exmoor Devon / Somerset12,005.31954 Note that several of these Sites of Special Scientific Interest have adjacent protected areas that are contiguous and so the total contiguous area of land that is protected can be larger than these figures. e.g. Upper Teesdale SSSI and Moorhouse and Cross Fell SSSI form a continuous area of protection.

Sites more than 4000 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres South Dartmoor Devon9,668.21952 Hexhamshire Moors County Durham / Northumberland9,433.91998 Kielderhead and Emblehope Moors Northumberland8,254.41971 Eastern Peak District Moors South Yorkshire / ?8,094.41955 Bollihope, Pikestone, Eggleston and Woodland Fells County Durham7,949.2 1996 North Norfolk Coast Norfolk7,700.01954 Duddon Estuary Cumbria6,806.31990 (amalgamated 5) Mersey Estuary Cheshire / Merseyside6,702.11951 The Swale Kent6,568.41968 Blackwater Estuary Essex5,738.01955 South Thames Estuary and Marshes Kent5,449.11951 Bodmin Moor, North Cornwall4,957.01951 Kielder Mires Cumbria / Northumberland4,818.01995 Bowes Moor County Durham4,457.71989 Poole Harbour Dorset4,049.01964

Sites more than 2000 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Chichester Harbour Hampshire / West Sussex3,695.01970 Bridgwater Bay Somerset3,574.11989 Dungeness East Sussex / Kent3,241.71951 Ashdown Forest East Sussex3,144.61953 South Exmoor Devon / Somerset3,132.71992 Long Mynd Shropshire2,637.61953 Alde-Ore Estuary Suffolk2,554.31952 The Quantocks Somerset2,506.91970 Ouse Washes Cambridgeshire / Norfolk2,403.01955 Exe Estuary Devon2,186.61952 East Dartmoor Devon2,088.11976 Langstone Harbour Hampshire2,069.41958

Sites more than 1500 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Thorne Crowle and Goole Moors East Riding / South Yorkshire1,918.61970 Windsor Forest and Great Park Berkshire / Surrey1,771.21973 Exmoor Coastal Heaths Somerset1,758.31994 Wyre Forest Shropshire / Hereford & Worcester1,753.71955 Epping Forest Essex / Greater London1,728.01953 Porton Down Wiltshire1,561.81977 Rutland Water Leicestershire1,540.11981

Sites more than 1000 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Upper Severn Estuary Gloucestershire1,436.81954 Tamar - Tavy Estuary Cornwall / Devon1,422.31991 Hatfield Moors South Yorkshire1,400.71954 Avon Valley (Bickton to Christchurch) Dorset / Hampshire1,383.71974 Braunton Burrows Devon1,356.71952 Taw-Torridge Estuary Devon1,336.51981 Nene Washes Cambridgeshire1,310.01959 Portsmouth Harbour Hampshire1,266.11974 East Devon Pebblebed Heaths Devon1,111.91952 Catcott, Edington and Chilton Moors Somerset1,083.01967 West Sedgemoor Somerset1,016.01983 Haldon Forest Devon1,013.21992

Sites more than 750 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Chesil and the Fleet Dorset990.41952 Fenn's, Whixall, Bettisfield, Wem and Cadney Mosses Shropshire / Wales948.41953 Tealham and Tadham Moors Somerset917.61985 Savernake Forest Wiltshire904.71971 King's Sedgemoor Somerset822.01985 Grafham Water Cambridgeshire811.91986 Durham Coast Cleveland / Durham765.41960 Rye Harbour East Sussex761.11953 Studland and Godlingston Heath Dorset758.91954

Sites more than 500 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Blue Anchor to Lilstock Coast Somerset742.81971 Abberton Reservoir Essex716.31955 Lynher Estuary Cornwall687.31951 North Moor Somerset676.31986 Cotswold Commons And Beechwoods Gloucestershire665.51954 Bentley Wood Wiltshire / Hampshire665.01985 Barle Valley Somerset622.91954 Pagham Harbour West Sussex615.91954 Upper Fal estuary and woodlands Cornwall603.51968 Chew Valley Lake Avon565.21971 Arne Dorset563.41986 Westhay Moor Somerset513.71971 Breydon Water Norfolk506.51987

Sites more than 400 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Wet Moor Somerset491.01985 Curry and Hay Moors Somerset472.81992 Dunster Park and Heathlands Somerset466.62000 Cranborne Chase Dorset / Wiltshire451.41975 Cheddar Complex Somerset441.31952 Blithfield Reservoir Staffordshire435.61968 Winterton to Horsey Dunes Norfolk427.21954 Wytham Woods Oxfordshire426.51950

Sites more than 300 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Bratton Downs Wiltshire395.81971 Shapwick Heath Somerset394.01967 South Gare and Coatham Sands Cleveland381.21971 Isle of Portland Dorset369.31952 Christchurch Harbour Dorset353.21964 Lundy Devon345.01976 Axmouth to Lyme Regis Undercliffs Devon / ?334.61952 Crook Peak to Shute Shelve Hill Somerset332.2820.91952 Fyfield Down Wiltshire325.31951 Seaton Dunes And Common Cleveland312.11966 Pewsey Downs Wiltshire305.31951

Sites more than 250 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Church Wood, Blean Kent297.11951 Seal Sands Cleveland294.41966 Lower Woods Avon280.11966 Greenham and Crookham Commons Berkshire278.6 & 1985 Lower Fal & Helford Intertidal Cornwall277.71997 Tees and Hartlepool Foreshore and Wetlands Cleveland255.6 & 1997 Skipwith Common North Yorkshire 2741958 Slapton Ley Devon254.72004

Sites more than 200 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Longleat Woods Somerset249.91972 Mottisfont Bats Hampshire231.02003 Moorlinch Somerset226.01985 West Moor Somerset213.01985 Otmoor Oxfordshire211.61952 Blagdon Lake Avon212.71971 Ashton Court Avon210.31998

Sites more than 150 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Berrow Dunes Somerset200.01952 Southlake Moor Somerset196.11985 Brimsdown Hill Wiltshire193.71951 Porlock Ridge and Saltmarsh Somerset186.31990 Langmead and Weston Level Somerset168.81991 Gordano Valley Avon161.71971 East Blean Woods Kent156.81981 St. Catherine's Valley Avon156.11997 Avon Gorge Avon155.41952 Black Down and Sampford Commons Somerset155.21952 Brimble Pit and Cross Swallet Basins Somerset154.31987

Sites more than 100 hectares in size Site name Area of Search Reason for designation Area Grid reference Year in which notified Map Biological interest Geological interest Hectares Acres Attenborough Nature Reserve Nottinghamshire226.61982 Asham Wood Somerset141.61963 Burrington Combe Avon / North Somerset139.11952 Wenlock Edge Shropshire136.81954 Tickenham, Nailsea and Kenn Moors Avon129.41995 Bowerchalke Downs Wiltshire128.61971 Calstone And Cherhill Downs Wiltshire128.61971 King's Wood and Urchin Wood Avon128.11990 East Polden Grasslands Somerset124.01999 Upper Fowey Valley Cornwall124.01989 Potteric Carr South Yorkshire119.61977 Cowpen Marsh Cleveland116.81966 River Kennet Berkshire / Wiltshire112.71995 Cheddar Reservoir Somerset105.41972 River Barle Somerset104.21997 Dozmary Pool Cornwall104.21986 Prior's Park & Adcombe Wood Somerset103.61952

Notes Data rounded to one decimal place. Link to maps using the Nature on the Map service provided by English Nature.