This study illustrates that clouds or parcels of new water enter a fjord of Puget Sound in pulses. The mixing pattern of one of these parcels is examined using an analytical solution to an advection-diffusion equation. The parcel or extended-source is treated theoretically by superposition of point-sources. The analysis is simplified by first considering the initial interval of negligible shear-effect. The length of this interval is estimated using a variance defect criterion and coincides with independent calculations of heat budgets. During the interval the vertical and horizontal eddy diffusivities were found to be K z = 0·7 cm 2 s −1 and K x = 7·7 × 10 4 cm 2 s −1, respectively. The water parcel was observed for a week above sill depth (120 m) in a roughly 20 × 3 × 0·18 km fjord (Dabob Bay). It initially measured 60 m × 8 km along channel and was circumscribed by sharp gradients of conservative and non-conservative water properties. Field measurements were obtained with a salinity-temperature-depth (STD) system at 2 m × 1 km vertical and horizontal intervals, respectively, and were supplemented by conventional observations of dissolved oxygen.