Monitoring the water resources from Space is a rapidly developing area of application for radar altimetry. Recent progress in instrumentation (development of SAR and SARIn altimeter sensors) and radar signal treatment has allowed us for the first time to include medium and small continental water objects in the scope of application of altimetry. In the Republic of Ireland only the lakes with area more than 10 km2 are included in the in situ water level observational network. This represents only 30% of the total lake area. The island dimensions (~84 400 km2) limit development of long fluvial networks. As a result, the width of even the largest river channels does not exceed 250 m and ranges mainly within 20 - 100 m. The potential of radar altimetry for monitoring lakes of 2-4 km2 area and rivers of 80-200 m width has already been demonstrated in prior studies. We explore the capacity of the most recent generation of satellite altimetry missions (Jason-3, CryoSat-2, and Sentinel-3) for monitoring water bodies, water courses and water regime of peatlands on the entire territory of the Republic of Ireland. In the framework of the ESA HYDROCOASTAL Project we 1) investigated the performance of SAR (Sentinel-3) and conventional (Jason-2,-3) altimetry to retrieve water level time series, 2) evaluated the advantage of enhanced (80Hz) Sentinel-3 sampling rate processing provided by the ESA G-POD/SARvatore online and on-demand SAR Altimetry Processing Service and 3) examined the gain from the combination of measurements of repeat-orbit (Sentinel-3) and geodetic-orbit (CryoSat-2) satellite missions. We also investigated an effect of river width and configuration of the fluvial virtual station on the accuracy of the water height retrievals as well as assessed the impacts of the surrounding relief on the performance of satellites to produce high quality altimetric water level time series that may be of value to a broad variety of users.