The High Resolution Imaging Science Experiment (HiRISE) on board NASA’s Mars Reconnaissance Orbiter has been returning data for 3 Martian years. These data show that Mars is more dynamic than previously believed. In particular, the high-resolution images (down to 25 cm/px) have given us new insight into seasonal processes. When combined with the observations of the CRISM imagingspectrometer, we begin to obtain a rather detailed picture of how phenomena develop over time.