This dataset comprises 3D volumes that display the converted mean mass concentrations of suspended particulate matter (SPMC) for different size ranges (1-500 µm, 1-3 µm, 3-20 µm, 20-200 µm, 200-500 µm). These 3D grids (2 m resolution) were made for five campaigns, which were conducted during 2020-2021 in the Belgian part of the North Sea. This dataset was used in the research article in Remote Sensing titled "The potential of multibeam sonars as 3D turbidity and SPM monitoring tool in the North Sea" by Praet et al. (2023). ... : Five campaigns were conducted with the RV Simon Stevin in the Kwinte (KW) and Westdiep (WD) areas during fall/winter (October 2020, February 2021) and spring/summer (March 2021, May 2021, July 2021). During each campaign, 3D multibeam water column (EM2040) and in-situ optical sensor (LISST-200X) datasets were collected to yield an empirical relation using linear regression modelling. This relationship was then used to predict SPM volume concentrations from the 3D acoustic measurements, which were further converted to SPM mass concentrations using calculated densities. The raw and processed LISST-200X datasets can be consulted on the Marine Data Archive (DOI: doi.org/10.14284/572). This research was conducted in the framework of the TIMBERS project (grant number SR/00/381), the STURMAPSS (dissemination) project (grant number SR/L9/221) and the TURBEAMS project (grant number RV/21/TURBEAMS). All projects were funded by the Belgian Science Policy Office BELSPO. ...