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[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
The Wash	Norfolk / Lincolnshire	Y		63,135.0	156,010.0	TF550400	1972
North York Moors	North Yorkshire / Cleveland	Y		44,087.7	108,943.1	NZ680000	1998
Humber Estuary	East Riding of Yorkshire / Lincolnshire	Y	Y	37,000.6	91,430.5	TA216184	2004
Dark Peak	Derbyshire / Greater Manchester / South Yorkshire / West Yorkshire	Y	Y	31,852.9	78,710.2	SK110960	1951
Morecambe Bay	Cumbria / Lancashire	Y		30,287.5	74,842.0	SD360700	1975
Upper Solway Flats and Marshes	Cumbria / ?	Y	Y	29,950.5	74,009.3	NY160610	1988
The New Forest	Hampshire / Wiltshire	Y	Y	28,947.4	71,530.6	SU298081	1959	Map
South Pennine Moors	West Yorkshire / Great Manchester / Lancashire / North Yorkshire	Y	Y	20,938.1	51,739.2	SD920300	1994
Salisbury Plain	Wiltshire / Hampshire	Y		19,689.9	48,654.8	SU070500	1975	Map
Breckland Forest	Norfolk / Suffolk	Y	Y	18,078.7	44,673.4	TL819839	2000
Severn Estuary	Avon / Somerset + others	Y	Y	15,950.0	39,413.3	ST480830	1976
Upper Teesdale	County Durham	Y	Y	14,035.6	34,682.7	NY830320	1951
Moorhouse and Cross Fell	Cumbria / County Durham	Y	Y	13,707.0	33,870.7	NY715365	1990
Dee Estuary	Cheshire / Clwyd	Y		13,679.7	33,803.3	SJ220800	1954
Breckland Farmland	Norfolk / Suffolk	Y		13,335.7	32,953.2	TL762783	2000
North Dartmoor	Devon	Y	Y	13,413.2	33,144.7	SX580850	1952
North Exmoor	Devon / Somerset	Y	Y	12,005.3	29,665.7	SS800430	1954

Sites more than 4000 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
South Dartmoor	Devon	Y	Y	9,668.2	23,890.6	SX630690	1952
Hexhamshire Moors	County Durham / Northumberland	Y		9,433.9	23,311.7	NY870530	1998	Map
Kielderhead and Emblehope Moors	Northumberland	Y		8,254.4	20,397.1	NT700000	1971
Eastern Peak District Moors	South Yorkshire / ?	Y	Y	8,094.4	20,001.7	SK270770	1955	Map
Bollihope, Pikestone, Eggleston and Woodland Fells	County Durham	Y		7,949.2	19,642.9	NZ005300	1996	Map
North Norfolk Coast	Norfolk	Y	Y	7,700.0	19,027.1	TG020440	1954
Duddon Estuary	Cumbria	Y	Y	6,806.3	16,818.7	SD151753	1990 (amalgamated 5)	Map
Mersey Estuary	Cheshire / Merseyside	Y		6,702.1	16,561.2	SJ440800	1951
The Swale	Kent	Y	Y	6,568.4	16,230.9	TR000670	1968
Blackwater Estuary	Essex	Y	Y	5,738.0	14,178.9	TL940070	1955
South Thames Estuary and Marshes	Kent	Y		5,449.1	13,465.0	TQ770785	1951
Bodmin Moor, North	Cornwall	Y		4,957.0	12,249.0	SX160810	1951
Kielder Mires	Cumbria / Northumberland	Y		4,818.0	11,905.5	NY670800	1995
Bowes Moor	County Durham	Y		4,457.7	11,015.2	NY923104	1989	Map
Poole Harbour	Dorset	Y		4,049.0	10,005.3	SZ000890	1964

Sites more than 2000 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Chichester Harbour	Hampshire / West Sussex	Y	Y	3,695.0	9,130.5	SU760000	1970
Bridgwater Bay	Somerset	Y		3,574.1	8,831.8	ST290480	1989
Dungeness	East Sussex / Kent	Y	Y	3,241.7	8,010.4	TR050180	1951
Ashdown Forest	East Sussex	Y		3,144.6	7,770.5	TQ450300	1953
South Exmoor	Devon / Somerset	Y		3,132.7	7,741.1	SS880340	1992
Long Mynd	Shropshire	Y	Y	2,637.6	6,517.7	SO420950	1953
Alde-Ore Estuary	Suffolk	Y		2,554.3	6,311.8	TM394757	1952
The Quantocks	Somerset	Y		2,506.9	6,194.7	ST140390	1970	Map
Ouse Washes	Cambridgeshire / Norfolk	Y		2,403.0	5,937.9	TL482867	1955
Exe Estuary	Devon	Y	Y	2,186.6	5,403.2	SX980845	1952
East Dartmoor	Devon	Y	Y	2,088.1	5,159.8	SX695815	1976
Langstone Harbour	Hampshire	Y		2,069.4	5,113.6	SU700030	1958

Sites more than 1500 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Thorne Crowle and Goole Moors	East Riding / South Yorkshire	Y		1,918.6	4,741.0	SE730160	1970
Windsor Forest and Great Park	Berkshire / Surrey	Y		1,771.2	4,376.7	SU970685	1973
Exmoor Coastal Heaths	Somerset	Y		1,758.3	4,344.9	SS620480	1994	Map
Wyre Forest	Shropshire / Hereford & Worcester	Y		1,753.7	4,333.5	SS750760	1955
Epping Forest	Essex / Greater London	Y		1,728.0	4,270.0	TL475035	1953
Porton Down	Wiltshire	Y		1,561.8	3,859.3	SU240365	1977	Map
Rutland Water	Leicestershire	Y		1,540.1	3,805.7	SK928070	1981

Sites more than 1000 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Upper Severn Estuary	Gloucestershire	Y		1,436.8	3,550.4	SO720060	1954	Map
Tamar - Tavy Estuary	Cornwall / Devon	Y		1,422.3	3,514.6	SX474650	1991
Hatfield Moors	South Yorkshire	Y		1,400.7	3,461.2	SE705060	1954
Avon Valley (Bickton to Christchurch)	Dorset / Hampshire	Y		1,383.7	3,419.2	TU147123	1974
Braunton Burrows	Devon	Y	Y	1,356.7	3,352.5	SS430350	1952
Taw-Torridge Estuary	Devon	Y		1,336.5	3,302.6	SS470310	1981
Nene Washes	Cambridgeshire	Y		1,310.0	3,237.1	TL200977	1959
Portsmouth Harbour	Hampshire	Y		1,266.1	3,128.6	SU620035	1974
East Devon Pebblebed Heaths	Devon	Y		1,111.9	2,747.6	SY050880	1952
Catcott, Edington and Chilton Moors	Somerset	Y		1,083.0	2,676.2	ST390420	1967	Map
West Sedgemoor	Somerset	Y		1,016.0	2,510.6	ST361258	1983	Map
Haldon Forest	Devon	Y		1,013.2	2,503.7	SX886838	1992	Map

Sites more than 750 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Chesil and the Fleet	Dorset	Y	Y	990.4	2,447.3	SY496885	1952
Fenn's, Whixall, Bettisfield, Wem and Cadney Mosses	Shropshire / Wales	Y		948.4	2,343.5	SJ490365	1953
Tealham and Tadham Moors	Somerset	Y		917.6	2,267.4	ST420450	1985	Map
Savernake Forest	Wiltshire	Y		904.7	2,235.6	SU215665	1971	Map
King's Sedgemoor	Somerset	Y		822.0	2,031.2	ST400330	1985
Grafham Water	Cambridgeshire	Y		811.9	2,006.2	TL150680	1986
Durham Coast	Cleveland / Durham	Y	Y	765.4	1,891.3	NZ400500	1960
Rye Harbour	East Sussex	Y	Y	761.1	1,880.7	TQ935180	1953	Map
Studland and Godlingston Heath	Dorset	Y	Y	758.9	1,875.3	SZ030845	1954

Sites more than 500 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Blue Anchor to Lilstock Coast	Somerset		Y	742.8	1,835.5	ST033435	1971
Abberton Reservoir	Essex	Y		716.3	1,770.0	TL970180	1955
Lynher Estuary	Cornwall	Y		687.3	1,698.4	SX375565	1951
North Moor	Somerset	Y		676.3	1,671.2	ST325305	1986
Cotswold Commons And Beechwoods	Gloucestershire	Y		665.5	1,644.5	SP900130	1954	Map
Bentley Wood	Wiltshire / Hampshire	Y		665.0	1,643.3	SU250295	1985	Map
Barle Valley	Somerset	Y		622.9	1,539.2	SS850349	1954
Pagham Harbour	West Sussex	Y	Y	615.9	1,521.9	SZ875970	1954
Upper Fal estuary and woodlands	Cornwall	Y		603.5	1,491.3	SW850410	1968
Chew Valley Lake	Avon	Y		565.2	1,396.6	ST570600	1971
Arne	Dorset	Y	Y	563.4	1,392.2	ST966880	1986
Westhay Moor	Somerset	Y		513.7	1,269.4	ST455445	1971	Map
Breydon Water	Norfolk	Y		506.5	1,251.6	TG500075	1987	Map

Sites more than 400 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Wet Moor	Somerset	Y		491.0	1,213.3	ST448244	1985	Map
Curry and Hay Moors	Somerset	Y		472.8	1,168.3	ST323273	1992	Map
Dunster Park and Heathlands	Somerset	Y		466.6	1,153.0	SS955441	2000	Map
Cranborne Chase	Dorset / Wiltshire	Y		451.4	1,115.4	ST970180	1975	Map
Cheddar Complex	Somerset	Y	Y	441.3	1,090.5	ST465538	1952	Map
Blithfield Reservoir	Staffordshire	Y		435.6	1,076.4	SK057242	1968
Winterton to Horsey Dunes	Norfolk	Y	Y	427.2	1,055.6	ST490210	1954
Wytham Woods	Oxfordshire	Y		426.5	1,053.9	SP462083	1950

Sites more than 300 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Bratton Downs	Wiltshire	Y	Y	395.8	978.0	ST925522	1971	Map
Shapwick Heath	Somerset	Y		394.0	973.6	ST430403	1967	Map
South Gare and Coatham Sands	Cleveland	Y		381.2	942.0	NZ582263	1971
Isle of Portland	Dorset	Y	Y	369.3	912.6	SY690722	1952
Christchurch Harbour	Dorset	Y	Y	353.2	872.8	SZ175915	1964
Lundy	Devon	Y		345.0	852.5	SS135460	1976
Axmouth to Lyme Regis Undercliffs	Devon / ?	Y	Y	334.6	826.8	SY300900	1952
Crook Peak to Shute Shelve Hill	Somerset	Y	Y	332.2	820.9	ST385555	1952	Map
Fyfield Down	Wiltshire	Y	Y	325.3	803.8	SU136709	1951	Map
Seaton Dunes And Common	Cleveland	Y		312.1	771.2	NZ535285	1966
Pewsey Downs	Wiltshire	Y		305.3	754.4	SU113636	1951	Map

Sites more than 250 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Church Wood, Blean	Kent	Y		297.1	734.2	TR109603	1951
Seal Sands	Cleveland	Y		294.4	727.5	NZ529260	1966
Lower Woods	Avon	Y	Y	280.1	692.1	ST743876	1966
Greenham and Crookham Commons	Berkshire	Y		278.6	688.4	SU490645 & SU523643	1985
Lower Fal & Helford Intertidal	Cornwall	Y		277.7	686.2	SW860334	1997
Tees and Hartlepool Foreshore and Wetlands	Cleveland	Y		255.6	631.6	NZ516348 & NZ505224	1997
Skipwith Common	North Yorkshire	Y		274	677.1	SE668362	1958
Slapton Ley	Devon	Y	Y	254.7	629.4	SX826440	2004

Sites more than 200 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Longleat Woods	Somerset	Y		249.9	617.5	ST795435	1972	Map
Mottisfont Bats	Hampshire	Y		231.0	570.8	SU314281	2003
Moorlinch	Somerset	Y		226.0	558.5	ST390360	1985	Map
West Moor	Somerset	Y		213.0	526.3	ST420220	1985	Map
Otmoor	Oxfordshire	Y		211.6	522.9	SP575130	1952
Blagdon Lake	Avon	Y		212.7	525.6	ST515597	1971
Ashton Court	Avon	Y		210.3	519.7	ST553723	1998

Sites more than 150 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Berrow Dunes	Somerset	Y		200.0	494.2	ST293520	1952
Southlake Moor	Somerset	Y		196.1	484.6	ST370300	1985	Map
Brimsdown Hill	Wiltshire	Y		193.7	478.6	SU831385	1951	Map
Porlock Ridge and Saltmarsh	Somerset	Y	Y	186.3	460.4	SS880479	1990	Map
Langmead and Weston Level	Somerset	Y		168.8	417.1	ST353330	1991
Gordano Valley	Avon	Y	Y	161.7	399.6	ST435730	1971
East Blean Woods	Kent	Y		156.8	387.5	TR189640	1981
St. Catherine's Valley	Avon	Y		156.1	385.7	ST760725	1997
Avon Gorge	Avon	Y	Y	155.4	384.0	ST560743	1952
Black Down and Sampford Commons	Somerset	Y		155.2	383.5	ST118161	1952
Brimble Pit and Cross Swallet Basins	Somerset		Y	154.3	381.3	ST512505	1987

Sites more than 100 hectares in size

Site name	Area of Search	Reason for designation		Area[ a]		Grid reference	Year in which notified	Map[B]
		Biological interest	Geological interest	Hectares	Acres
Attenborough Nature Reserve	Nottinghamshire	Y		226.6	559.9	SK514338	1982	Map
Asham Wood	Somerset	Y		141.6	349.9	ST705460	1963
Burrington Combe	Avon / North Somerset	Y	Y	139.1	343.7	ST478583	1952
Wenlock Edge	Shropshire	Y	Y	136.8	338.0	SO606995	1954
Tickenham, Nailsea and Kenn Moors	Avon	Y		129.4	319.8	ST440700	1995
Bowerchalke Downs	Wiltshire	Y		128.6	317.8	SU004218	1971	Map
Calstone And Cherhill Downs	Wiltshire	Y		128.6	317.8	SU047692	1971	Map
King's Wood and Urchin Wood	Avon	Y		128.1	316.5	ST454645	1990
East Polden Grasslands	Somerset	Y		124.0	306.4	ST474325	1999	Map
Upper Fowey Valley	Cornwall	Y		124.0	306.4	SX215730	1989
Potteric Carr	South Yorkshire	Y		119.6	295.5	SE599003	1977
Cowpen Marsh	Cleveland	Y		116.8	288.6	NZ500529	1966
River Kennet	Berkshire / Wiltshire	Y		112.7	278.5	SU203692	1995	Map
Cheddar Reservoir	Somerset	Y		105.4	260.4	ST441537	1972	Map
River Barle	Somerset	Y		104.2	257.5	SS723423	1997	Map
Dozmary Pool	Cornwall	Y	Y	104.2	257.5	SX195745	1986
Prior's Park & Adcombe Wood	Somerset	Y		103.6	256.0	ST225170	1952	Map

Notes

^a Data rounded to one decimal place.

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