The variation of oceanic whitecap coverage with wind speed was determined from the analysis of group, of five or more photographs taken, along with measurements of wind speed and air and water temperatures, during each of 71 observation periods at locations on the Atlantic Ocean and adjacent salt water bodies. The fraction of the sea surface covered by whitecaps is always <0.1% for wind speeds V<4 m sec−1. For winds from 4 to 10 m sec−1 the maximum percentage of the sea surface covered by whitecaps is given by W=0.00135 V3.4. Abstract The variation of oceanic whitecap coverage with wind speed was determined from the analysis of group, of five or more photographs taken, along with measurements of wind speed and air and water temperatures, during each of 71 observation periods at locations on the Atlantic Ocean and adjacent salt water bodies. The fraction of the sea surface covered by whitecaps is always <0.1% for wind speeds V<4 m sec−1. For winds from 4 to 10 m sec−1 the maximum percentage of the sea surface covered by whitecaps is given by W=0.00135 V3.4.