Martham Broad

Martham Broad is a National Nature Reserve maintained by English Nature on the River Thurne in the county of Norfolk, England, within The Broads National Park. It is part of the Upper Thurne Broads and Marshes SSSI (Site of Special Scientific Interest), and it is owned and managed by Norfolk Wildlife Trust.

It comprises 59 hectares of open water, reed and saw-sedge fen, and it is a shallow, brackish lake. The reed swamp consists of common reed and lesser reedmace. In summer, the swallowtail butterfly can be seen.

Boats can only use a narrow marked channel; they are discouragesd from using the broad during the winter months because of the breeding season. There is a footpath through the reserve.