We describe observations of fine structure in a turbulent tidal channel on the British Columbia coast obtained with towed and vertical conductivity, temperature, and depth profiles and a novel acoustic technique. The acoustic scheme involves the detection of the scattering of sound waves by fine structure moving through a pair of acoustic paths that traverse the channel. The larger scale flow and also the fine structure can be observed in this way, providing a time series measurement of the flow properties as the tidal current changes. The channel is characterized by periods of intense mixing through most of the tidal cycle. Near slack water it becomes stratified, and although it remains active, the outer scale of the turbulence decreases to 2--3 m. The fine-scale variability is a sensitive function of flow speed and stratification. ¿American Geophysical Union 1987