List of the largest Sites of Special Scientific Interest in England explained

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 / Lincolnshire			63,135.0	631351NaN1		1972
North York Moors	North Yorkshire / Cleveland			44,087.7	44087.71NaN1		1998
Humber Estuary	East Riding of Yorkshire / Lincolnshire			37,000.6	37000.61NaN1		2004
Dark Peak	Derbyshire / Greater Manchester / South Yorkshire / West Yorkshire			31,852.9	31852.91NaN1		1951
Morecambe Bay	Cumbria / Lancashire			30,287.5	30287.51NaN1		1975
Upper Solway Flats and Marshes	Cumbria / ?			29,950.5	29950.51NaN1		1988
The New Forest	Hampshire / Wiltshire			28,947.4	28947.41NaN1		1959
South Pennine Moors	West Yorkshire / Great Manchester / Lancashire / North Yorkshire			20,938.1	20938.11NaN1		1994
Salisbury Plain	Wiltshire / Hampshire			19,689.9	19689.91NaN1		1975
Breckland Forest	Norfolk / Suffolk			18,078.7	18078.71NaN1		2000
Severn Estuary	Avon / Somerset + others			15,950.0	159501NaN1		1976
Upper Teesdale	County Durham			14,035.6	14035.61NaN1		1951
Moorhouse and Cross Fell	Cumbria / County Durham			13,707.0	137071NaN1		1990
Dee Estuary	Cheshire / Clwyd			13,679.7	13679.71NaN1		1954
Breckland Farmland	Norfolk / Suffolk			13,335.7	13335.71NaN1		2000
North Dartmoor	Devon			13,413.2	13413.21NaN1		1952
North Exmoor	Devon / Somerset			12,005.3	12005.31NaN1		1954

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	Devon			9,668.2	9668.21NaN1		1952
Hexhamshire Moors	County Durham / Northumberland			9,433.9	9433.91NaN1		1998
Kielderhead and Emblehope Moors	Northumberland			8,254.4	8254.41NaN1		1971
Eastern Peak District Moors	South Yorkshire / ?			8,094.4	8094.41NaN1		1955
Bollihope, Pikestone, Eggleston and Woodland Fells	County Durham			7,949.2	7949.21NaN1		1996
North Norfolk Coast	Norfolk			7,700.0	77001NaN1		1954
Duddon Estuary	Cumbria			6,806.3	6806.31NaN1		1990 (amalgamated 5)
Mersey Estuary	Cheshire / Merseyside			6,702.1	6702.11NaN1		1951
The Swale	Kent			6,568.4	6568.41NaN1		1968
Blackwater Estuary	Essex			5,738.0	57381NaN1		1955
South Thames Estuary and Marshes	Kent			5,449.1	5449.11NaN1		1951
Bodmin Moor, North	Cornwall			4,957.0	49571NaN1		1951
Kielder Mires	Cumbria / Northumberland			4,818.0	48181NaN1		1995
Bowes Moor	County Durham			4,457.7	4457.71NaN1		1989
Poole Harbour	Dorset			4,049.0	40491NaN1		1964

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 Sussex			3,695.0	36951NaN1		1970
Bridgwater Bay	Somerset			3,574.1	3574.11NaN1		1989
Dungeness	East Sussex / Kent			3,241.7	3241.71NaN1		1951
Ashdown Forest	East Sussex			3,144.6	3144.61NaN1		1953
South Exmoor	Devon / Somerset			3,132.7	3132.71NaN1		1992
Long Mynd	Shropshire			2,637.6	2637.61NaN1		1953
Alde-Ore Estuary	Suffolk			2,554.3	2554.31NaN1		1952
The Quantocks	Somerset			2,506.9	2506.91NaN1		1970
Ouse Washes	Cambridgeshire / Norfolk			2,403.0	24031NaN1		1955
Exe Estuary	Devon			2,186.6	2186.61NaN1		1952
East Dartmoor	Devon			2,088.1	2088.11NaN1		1976
Langstone Harbour	Hampshire			2,069.4	2069.41NaN1		1958

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 Yorkshire			1,918.6	1918.61NaN1		1970
Windsor Forest and Great Park	Berkshire / Surrey			1,771.2	1771.21NaN1		1973
Exmoor Coastal Heaths	Somerset			1,758.3	1758.31NaN1		1994
Wyre Forest	Shropshire / Hereford & Worcester			1,753.7	1753.71NaN1		1955
Epping Forest	Essex / Greater London			1,728.0	17281NaN1		1953
Porton Down	Wiltshire			1,561.8	1561.81NaN1		1977
Rutland Water	Leicestershire			1,540.1	1540.11NaN1		1981

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	Gloucestershire			1,436.8	1436.81NaN1		1954
Tamar - Tavy Estuary	Cornwall / Devon			1,422.3	1422.31NaN1		1991
Hatfield Moors	South Yorkshire			1,400.7	1400.71NaN1		1954
Avon Valley (Bickton to Christchurch)	Dorset / Hampshire			1,383.7	1383.71NaN1		1974
Braunton Burrows	Devon			1,356.7	1356.71NaN1		1952
Taw-Torridge Estuary	Devon			1,336.5	1336.51NaN1		1981
Nene Washes	Cambridgeshire			1,310.0	13101NaN1		1959
Portsmouth Harbour	Hampshire			1,266.1	1266.11NaN1		1974
East Devon Pebblebed Heaths	Devon			1,111.9	1111.91NaN1		1952
Catcott, Edington and Chilton Moors	Somerset			1,083.0	10831NaN1		1967
West Sedgemoor	Somerset			1,016.0	10161NaN1		1983
Haldon Forest	Devon			1,013.2	1013.21NaN1		1992

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	Dorset			990.4	990.41NaN1		1952
Fenn's, Whixall, Bettisfield, Wem and Cadney Mosses	Shropshire / Wales			948.4	948.41NaN1		1953
Tealham and Tadham Moors	Somerset			917.6	917.61NaN1		1985
Savernake Forest	Wiltshire			904.7	904.71NaN1		1971
King's Sedgemoor	Somerset			822.0	8221NaN1		1985
Grafham Water	Cambridgeshire			811.9	811.91NaN1		1986
Durham Coast	Cleveland / Durham			765.4	765.41NaN1		1960
Rye Harbour	East Sussex			761.1	761.11NaN1		1953
Studland and Godlingston Heath	Dorset			758.9	758.91NaN1		1954

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	Somerset			742.8	742.81NaN1		1971
Abberton Reservoir	Essex			716.3	716.31NaN1		1955
Lynher Estuary	Cornwall			687.3	687.31NaN1		1951
North Moor	Somerset			676.3	676.31NaN1		1986
Cotswold Commons And Beechwoods	Gloucestershire			665.5	665.51NaN1		1954
Bentley Wood	Wiltshire / Hampshire			665.0	6651NaN1		1985
Barle Valley	Somerset			622.9	622.91NaN1		1954
Pagham Harbour	West Sussex			615.9	615.91NaN1		1954
Upper Fal estuary and woodlands	Cornwall			603.5	603.51NaN1		1968
Chew Valley Lake	Avon			565.2	565.21NaN1		1971
Arne	Dorset			563.4	563.41NaN1		1986
Westhay Moor	Somerset			513.7	513.71NaN1		1971
Breydon Water	Norfolk			506.5	506.51NaN1		1987

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	Somerset			491.0	4911NaN1		1985
Curry and Hay Moors	Somerset			472.8	472.81NaN1		1992
Dunster Park and Heathlands	Somerset			466.6	466.61NaN1		2000
Cranborne Chase	Dorset / Wiltshire			451.4	451.41NaN1		1975
Cheddar Complex	Somerset			441.3	441.31NaN1		1952
Blithfield Reservoir	Staffordshire			435.6	435.61NaN1		1968
Winterton to Horsey Dunes	Norfolk			427.2	427.21NaN1		1954
Wytham Woods	Oxfordshire			426.5	426.51NaN1		1950

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	Wiltshire			395.8	395.81NaN1		1971
Shapwick Heath	Somerset			394.0	3941NaN1		1967
South Gare and Coatham Sands	Cleveland			381.2	381.21NaN1		1971
Isle of Portland	Dorset			369.3	369.31NaN1		1952
Christchurch Harbour	Dorset			353.2	353.21NaN1		1964
Lundy	Devon			345.0	3451NaN1		1976
Axmouth to Lyme Regis Undercliffs	Devon / ?			334.6	334.61NaN1		1952
Crook Peak to Shute Shelve Hill	Somerset			332.2	820.9		1952
Fyfield Down	Wiltshire			325.3	325.31NaN1		1951
Seaton Dunes And Common	Cleveland			312.1	312.11NaN1		1966
Pewsey Downs	Wiltshire			305.3	305.31NaN1		1951

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	Kent			297.1	297.11NaN1		1951
Seal Sands	Cleveland			294.4	294.41NaN1		1966
Lower Woods	Avon			280.1	280.11NaN1		1966
Greenham and Crookham Commons	Berkshire			278.6	278.61NaN1	&	1985
Lower Fal & Helford Intertidal	Cornwall			277.7	277.71NaN1		1997
Tees and Hartlepool Foreshore and Wetlands	Cleveland			255.6	255.61NaN1	&	1997
Skipwith Common	North Yorkshire			274	2741NaN1		1958
Slapton Ley	Devon			254.7	254.71NaN1		2004

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	Somerset			249.9	249.91NaN1		1972
Mottisfont Bats	Hampshire			231.0	2311NaN1		2003
Moorlinch	Somerset			226.0	2261NaN1		1985
West Moor	Somerset			213.0	2131NaN1		1985
Otmoor	Oxfordshire			211.6	211.61NaN1		1952
Blagdon Lake	Avon			212.7	212.71NaN1		1971
Ashton Court	Avon			210.3	210.31NaN1		1998

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	Somerset			200.0	2001NaN1		1952
Southlake Moor	Somerset			196.1	196.11NaN1		1985
Brimsdown Hill	Wiltshire			193.7	193.71NaN1		1951
Porlock Ridge and Saltmarsh	Somerset			186.3	186.31NaN1		1990
Langmead and Weston Level	Somerset			168.8	168.81NaN1		1991
Gordano Valley	Avon			161.7	161.71NaN1		1971
East Blean Woods	Kent			156.8	156.81NaN1		1981
St. Catherine's Valley	Avon			156.1	156.11NaN1		1997
Avon Gorge	Avon			155.4	155.41NaN1		1952
Black Down and Sampford Commons	Somerset			155.2	155.21NaN1		1952
Brimble Pit and Cross Swallet Basins	Somerset			154.3	154.31NaN1		1987

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	Nottinghamshire			226.6	226.61NaN1		1982
Asham Wood	Somerset			141.6	141.61NaN1		1963
Burrington Combe	Avon / North Somerset			139.1	139.11NaN1		1952
Wenlock Edge	Shropshire			136.8	136.81NaN1		1954
Tickenham, Nailsea and Kenn Moors	Avon			129.4	129.41NaN1		1995
Bowerchalke Downs	Wiltshire			128.6	128.61NaN1		1971
Calstone And Cherhill Downs	Wiltshire			128.6	128.61NaN1		1971
King's Wood and Urchin Wood	Avon			128.1	128.11NaN1		1990
East Polden Grasslands	Somerset			124.0	1241NaN1		1999
Upper Fowey Valley	Cornwall			124.0	1241NaN1		1989
Potteric Carr	South Yorkshire			119.6	119.61NaN1		1977
Cowpen Marsh	Cleveland			116.8	116.81NaN1		1966
River Kennet	Berkshire / Wiltshire			112.7	112.71NaN1		1995
Cheddar Reservoir	Somerset			105.4	105.41NaN1		1972
River Barle	Somerset			104.2	104.21NaN1		1997
Dozmary Pool	Cornwall			104.2	104.21NaN1		1986
Prior's Park & Adcombe Wood	Somerset			103.6	103.61NaN1		1952

Notes

Data rounded to one decimal place.

Link to maps using the Nature on the Map service provided by English Nature.