An experimental study on the impact of a translating two-dimensional transient jet on an initially quiescent liquid pool is studied experimentally using high-speed cinematic visualization and particle image velocimetry methods. Six jet conditions (covering a range of jet thicknesses, velocities and inclination angles relative to vertical) are considered, with measurements performed over a range of horizontal translation speeds for each jet condition. For all conditions studied herein, the jet penetrates into the pool and forms two craters – one upstream and one downstream of the jet. Gravity acts to close these craters, which after a short time pinch off at intermediate depths, thereby entrapping cavities of air. The translation speed of the jet is found to have a dramatic effect on the cavity shapes, pinch-off depths and pinch-off times. A simple theory based on a potential flow and a hydrostatically driven collapse is used to model this flow, and the resulting jet tip trajectories and cavity shapes compare favourably with the experimental data.