Fleam Dyke is a linear earthwork between Fulbourn and Balsham in Cambridgeshire, initiated at some timepoint between AD 330 and AD 510. It is three miles long and seven metres high from ditch to bank, and its ditch faces westwards, implying invading Saxons as its architects. Later, it formed a boundary of the Anglo-Saxon administrative division of Flendish Hundred. At a prominent point, the earthwork runs beside Mutlow Hill, crowned by a 4000-year-old Bronze Age burial mound.
Woodwalton Fen is a 209-hectare biological Site of Special Scientific Interest in the parish of Woodwalton, west of Ramsey in Huntingdonshire, Cambridgeshire, England. It is a Ramsar wetland site of international importance, a National Nature Reserve, a Special Area of Conservation and a Nature Conservation Review site, Grade I. The site is managed by Natural England.
Cornard Mere is an 8.5-hectare (21-acre) biological Site of Special Scientific Interest in Little Cornard in Suffolk. It is managed by the Suffolk Wildlife Trust.
Hopton Fen is a 15.3-hectare (38-acre) biological Site of Special Scientific Interest north of Hopton in Suffolk. It is managed by the Suffolk Wildlife Trust.
Blo' Norton and Thelnetham Fens are a 21.3-hectare (53-acre) biological Site of Special Scientific Interest (SSSI) on the Norfolk/Suffolk border. Blo' Norton Fen is in the parish of Blo' Norton in Norfolk and Thelnetham Fen is in Thelnetham parish in Suffolk. It is a Nature Conservation Review site, Grade 2, and part of the Waveney and Little Ouse Valley Fens Special Area of Conservation, Thelnetham Fen is managed by the Suffolk Wildlife Trust and Blo' Norton Fen by the Little Ouse Headwaters Project (LOHP).
Great Wilbraham Common is a 23.5-hectare (58-acre) biological Site of Special Scientific Interest west of Great Wilbraham in Cambridgeshire. It is managed by the Commons Right Holders.
Stow-Cum-Quy Fen is a 29.9-hectare (74-acre) biological Site of Special Scientific Interest west of Lode in Cambridgeshire. Most of it is common land.
Cavenham–Icklingham Heaths is a 419 hectare biological Site of Special Scientific Interest west of Icklingham in Suffolk. It is a Nature Conservation Review site, Grade I, and part of Breckland Special Area of Conservation and Breckland Special Protection Area under the European Union Directive on the Conservation of Wild Birds. Cavenham Heath is a 203.1 hectare National Nature Reserve.
Lakenheath Poor's Fen is a 5.2-hectare biological Site of Special Scientific Interest west of Lakenheath in Suffolk.
Pashford Poor's Fen, Lakenheath is a 12.4-hectare (31-acre) biological Site of Special Scientific Interest east of Lakenheath in Suffolk.
Stallode Wash, Lakenheath is a 34.1-hectare (84-acre) biological Site of Special Scientific Interest north-west of Lakenheath in Suffolk.
Bugg's Hole Fen is a 3.7-hectare (9.1-acre) biological Site of Special Scientific Interest north-west of Thelnetham in Suffolk.
Pakenham Meadows is a 5.8-hectare (14-acre) biological Site of Special Scientific Interest north of Pakenham in Suffolk.
Weston Fen is a 49.7-hectare (123-acre) biological Site of Special Scientific Interest in Hopton in Suffolk. It is part of the Waveney and Little Ouse Valley Fens Special Areas of Conservation, and an area of 37 hectares is managed as a nature reserve called Market Weston Fen by the Suffolk Wildlife Trust.
Leziate, Sugar and Derby Fens is an 87.9-hectare (217-acre) biological Site of Special Scientific Interest east of King's Lynn in Norfolk.
Boughton Fen is a 15.7-hectare (39-acre) biological Site of Special Scientific Interest east of Downham Market in Norfolk. it is common land registered to Boughton Parish Council.
Southrepps Common is a 5.6-hectare (14-acre) biological Site of Special Scientific Interest north of North Walsham in Norfolk. A larger area of 12.9-hectare (32-acre) is a Local Nature Reserve. It is owned by Southrepps Parish Council and managed by Southrepps Common Group. It is part of the Norfolk Valley Fens Special Area of Conservation.
Yare Broads and Marshes is a 744.5-hectare (1,840-acre) biological Site of Special Scientific Interest east of Norwich in Norfolk, England. Part of the site, is a Nature Conservation Review site, Grade I and most of it is in the Mid-Yare National Nature Reserve. It is part of the Broadland Ramsar site and Special Protection Area, and The Broads Special Area of Conservation. Two ares are Royal Society for the Protection of Birds nature reserves, Strumpshaw Fen and Surlingham Church Marsh.
Great Cressingham Fen is a 14.3-hectare (35-acre) biological Site of Special Scientific Interest near Great Cressingham in Norfolk. It is part of the Norfolk Valley Fens Special Area of Conservation.
