Orford Ness is one of the largest shingle deposits on the coast of Northern Europe. It has a distinctive triangular shape and is over 16 km in length from north to south.

At Aldeburgh, the tidal river Alde is turned south by the spit at Slaughden. The river then becomes the river Ore and flows south to exit into the sea at Shingle Street. South of Orford the river divides into two round Halvergate Island. In the Middle Ages the spit ended at Orford Ness leaving a wide bay between Orford and Hollesley at the mouth of the Butley river, but this has been closed off by the growth of the spit and now forms part of the estuary. The island is a nature reserve and bird sanctuary and is protected from flooding by embankments built above the level of the high tide.

During the storm of 1887 the southern most 2km of the spit was driven on shore and now lies from Shingle Street to Bawdsey.