This report is a contribution to the Strategic Environmental Assessment (SEA3) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). The report documents the known and likely occurrence of prehistoric archaeological remains across the whole floor of the North Sea including the SEA3 area, and makes suggestions on how to enhance the finding and reporting of such artefacts. Sea level change associated with the retreat of the last glaciation led to almost the whole floor of the North Sea being dry land at some time or another in the past 20,000 years. Similar exposure of the North Sea floor was also associated with earlier glacial cycles. Thus prehistoric submarine archaeological artefacts can occur over a wide area of the North Sea floor, as far north as the latitude of the Shetland Islands. While artefacts dating from the last 12,000 years are most likely, human or proto-human artefacts as old as half a million years may have survived in places. Submarine archaeological studies in the Danish Archipelago have established that coastal sites were an optimal place for prehistoric human occupation. Similar coastal sites existed over many parts of the North Sea floor in the past. The potential impact of oil and gas operations on submarine archaeological remains is discussed. Pipe entrenching is the most likely process to uncover prehistoric archaeological deposits.