We describe the results of a World Ocean Circulation Experiment (WOCE) survey (line P1W) from the open Pacific Ocean, through the Bussol' Strait and across the Sea of Okhotsk. Observations are presented of distributions of temperature and salinity, dissolved oxygen and nutrients, and some derived quantities. Discussion centers on the distribution of the Sea of Okhotsk component of the North Pacific Intermediate Water mass and its properties. The Sea of Okhotsk has been suggested as the only location where deep convection may occur within the North Pacific or its marginal seas. Our analysis suggests that the surface &sgr;&thgr;=26.85 has recently been ventilated, and arguments might be made to suggest that ventilation has occurred to &sgr;&thgr;=27.05. This is discussed here, but detailed evidence is covered in a companion paper analyzing CFC observations. The Okhotsk component of the North Pacific Intermediate Water extends to substantially greater depths and densities, and so some other process is needed to create the denser water mass. ¿ 1998 American Geophysical Union