To localise the particles in 3D and extract their instantaneous velocities, we use an in-house Machine Learning model (see Experimental Section, Supporting Information (Figure ) and for more details), which we train on experimental data (26924 total labelled observations). In agreement with previous experimental findings, we observe a orientation-dependent velocity with faster segments of motion out of plane in both directions compared to in-plane (see Figure , right), contrasting with the results of, where particle self-shadowing plays a critical role in determining microswimmer motion. Here, the orientation of the particle motion with respect to the substrate is defined by the angle between the velocity vectors for in-plane and out-of-plane motion (see Supporting Information, Figure for further information).