Four oceanographic surveys of the Pacific Ocean between the Canadian coast and Longitude 141° W. were undertaken in 1950, 1951 and 1952. The data are analysed to show the temperature, salinity and density structure, and the calculated currents. There isasurface zone about 100 to 150 metres deep in which all seasonal variations occur. This overlies a lower zone of more saline water of constant properties. The currents are weak and sinuous. It appears from these data and comparison with other work that the region lies in the divergence of the Sub-Arctic Current which divides to form the north-flowing Alaska Gyral and the south-flowing California Current. The identity and origins of the water masses are discussed.