In July 1972, six microstructure profiles were taken on the equator at 155¿W. The rate of dissipation of the temperature fluctuations &khgr; was high but not exceptional. A region of intense microstructure activity was found from 35 to 65 m, well above the velocity maximum. Sharp instabilities were found with vertical scales of less than 1 m in this region, and the average Cox number was >3300, implying the presence of intense vertical turbulence. By comparison, the profile in the vicinity of the velocity maximum, about 110 m, had an average Cox number of about 40 and a much less active appearance, which is consistent with weak vertical turbulence. A very well developed nearly isothermal region between 300 and 400 m the thermostad, was found to have a Cox number of about 100 because of moderate levels of microstructure activity. The thermostad was stable over scales of 10 m but not over scales of 1 m. Below the thermostad the mean Cox number was no more than 20, and the temperature profile had an appearance similar to that of monotonic records from other locations. The general pattern of vertical turbulence found is consistent with the 10-m-scale Richardson number values of Jones (1973) and with the values of the vertical turbulent viscosity used in a model by Robinson (1966).