Abstract The problem of the oscillatory motion of a homogeneous, rotating fluid in the vicinity of an isolated topographic feature is investigated in the laboratory and numerically. The laboratory experiments are conducted by fixing a cosine-squared body of revolution near the outer boundary of a circular tank rotating about a vertical axis with an angular velocity Ω(t)=Ω0+Ω1sinωt, where Ω0 is the mean background rotation and Ω0 and ω are the magnitude and frequency of an oscillatory component. Experiments with an oscillatory flow show clearly that a mean anticyclonic vortex is formed in the vicinity of the topographic feature. Surface floats are used to determine typical particle paths for various flow conditions and these are shown to vary markedly with the Rossby and temporal Rossby numbers of the background flow. Eulerian velocity profiles along and normal to the streamwise axis are used to quantify the anticyclonic vortex. A scaling analysis is advanced to show how the strength and distribution of th...