Publisher Summary This chapter describes the potential of high frequency (HF) radar for coastal and shelf sea monitoring. It demonstrates that HF radar can measure waves with high spatial resolution within 20kin of the coast and coarser resolution to over 100 km. Currents can be measured over roughly twice these distances. The potential of nesting such systems to provide data source for model development, testing, and assimilation and for validating satellite measurements is discussed in the chapter. It also provides a comparison between significant waveheight measurements made with the PISCES radar during a storm period in NURWEC2 with a WAVEC directional wave buoy and shows the directional spectra measured with this radar to the ranges of over 100 km. These all show a dominant swell component toward the north-east with a weaker wind wave spectrum toward the south or south-east, depending on the location. These components have been separated using a partitioning algorithm allowing significant waveheight and mean direction to be determined for each. These are plotted that shows the region of the experiment, the sites of the two radars, and of the WAVEC buoy. The spatial resolution of the measurements is coarser than that of the shorter range systems, but high resolution is not as important further offshore in most cases.