Breydon Water is a 514.4-hectare (1,271-acre) biological Site of Special Scientific Interest at Great Yarmouth, Norfolk. It is a Local Nature Reserve, a Ramsar site and a Special Protection Area. It is part of the Berney Marshes and Breydon Water nature reserve, which is managed by the Royal Society for the Protection of Birds (RSPB).

Great Yarmouth, often called Yarmouth, is a seaside town which gives its name to the wider Borough of Great Yarmouth in Norfolk, England; it straddles the River Yare and is located 20 miles (32 km) east of Norwich. Its fishing industry, mainly for herring, shrank after the mid-20th century and has all but ended. North Sea oil from the 1960s supplied an oil-rig industry that services offshore natural gas rigs; more recently, offshore wind power and other renewable energy industries have ensued.