Observations of the wave conditions around the Otago Peninsula were made during the period December 1963 to December 1964. From these observations the influence of sea and swell waves in developing the beaches and spits of this part of the Otago coastline has been assessed. The beaches, including the “southward”-pointing spits of the peninsula, have developed largely in response to a dominant southerly swell of of 10–15 sec. period, in spite of intense refraction. North of the peninsula, in an area sheltered from the swell, the dominant waves are produced by the north-easterly sea, which promotes some beach drift from north to south. The energy dominant waves and the evolution of shoreline curves on a coast of submergence are discussed.