The space-born gravity measurements of the Gravity Recovery and Climate Experiment (GRACE) allow estimates of mass redistributions on the surface of the Earth. In the oceans, local mass variability is associated with sea surface height, changes in the density structure and oceanic currents. Compared with the hydrological cycle over the continents, the oceanic signal is much smaller, with a signal amplitude of 1 to 5 cm of equivalent water height on a monthly timescale. Here, the performance of GRACE to realistically capture oceanic mass variability is assessed. GRACE solutions provided by different data centres (CSR, GFZ, JPL, ITG, GRGS) are validated against in-situ observations of Ocean Bottom Pressure (OBP), which is an integral measure of the oceanic and atmospheric mass. A database containing more than 80 deployments of OBP recorders in different oceanic regions allow a worldwide comparison. A spatial patch filtering method based on a numerical ocean model, is used to optimize the comparison between in-situ point measurements and the spatially-smoothed GRACE solutions. The advances made by the recent GRACE products are quantified. Further, the global distribution of in-situ measurements allows to identify regions where GRACE captures real oceanic variability (particularly in high latitudes), and regions where realistic estimates are still challenging.