Water samples were retrived during 5 campaigns (groundwater, piezometer or commercial wells (2009-2011) and one campaign at rivers (2011) along the southern coastline of the Puck Bay, southern Baltic Sea. Water samples were analyzed on-site for conductivity, temperature, and pH, and preserved for later major and trace elements, nutrients, water isotopes (H,O) and the C isotope composition of dissolved inorganc carbon in the laboratory (via ICP-OES, CF spectrophotometry, and isotope gas mass spectrometry). TA was determinend on-site. Selected samples were additionally dated by the 3H-3He technique. Ground water originates from different depths below surface and flow through different lithologies of different ages. It was the aim to characterize the composition of potential fresh water sources for surface or subsurface discharge into the Puck Bay, southern Baltic Sea.