Cavitation behind a circular cylinder is studied with the aid of highly time-resolved images at a constant Reynolds number of 64,000. Apart from recording the overall cavitation activity behind the cylinder, the study also delves into the dynamics of individual cavities. The length of cavity scales with cavitation number and this scaling is similar to the existing results obtained in flow regimes different from that presented here. Dynamics of individual cavities show distinct phases of cavity formation, growth, and collapse. At lower cavitation numbers, cavity collapse was followed by a rebounce. Variation of area normalized by the length of cavity shows self similarity in the growth phase of cavities for different cavitation numbers. Thus, the cavity length is the suitable length scale for dynamics of cavities, at least for the growth phase. The cavity lifetime scales inversely with the square of cavitation number. Dynamics of individual small cavity captured at higher frame rates was found to be similar to that of an isolated bubble. In this case, a rapid collapse follow a more gradual expansion phase, unlike that shown by larger cavities.