Beach porewater and streams at the coastline of Wismar Bay (Germany), southern Baltic Sea were investigated to evaluate the impact of diagenetic element fluxes and different fresh water sources, including submarine groundwater discharge, on the water column of the Wismar Bay (Germany), southern Baltic Sea. Beach porewater at five different sites between 0.4-1.8 m depth was extracted using push-point lances in July-August 2019. In addition, surface waters from four streams draining into the Wismar Bay were sampled at the mixing zone with the Baltic Sea. Both beach porewater and surface waters were analyzed for dissolved concentrations of major and trace elements and selected nutrients using ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), dissolved inorganic carbon (DIC) and δ13CDIC by means of Isotope-ratio-monitoring gas mass spectrometry (MAT 253 coupled to a Gasbench II), and δ18OH2O, δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I), and radium isotopes (223Ra, 224Ra) by radium-delayed coincidence counters (RaDeCC).