The proposed research aims to develop and test a new approach for assessing vulnerability of coastal aquifers to seawater intrusion to coastal flooding and pumping hazards, separately, along the Polish Baltic coast (an area of 9530 km2 with groundwater occurring mostly in complex multi-aquifer systems). Two overlay index methods were developed: the INTRUSFLD method, tailored to determine the vulnerability of the shallow aquifer (the first aquifer below the ground surface) to seawater intrusion resulting from coastal flooding and the INTRUSEXPL method to assess the vulnerability of the main (exploited) aquifer to seawater intrusion, considering groundwater pumping. An overlay index structure has been used in both cases assigning ratings and weights to several representative factors. All the analysis were processed using GIS tools, and the results are presented with a final map that categorize the groundwater vulnerability to seawater intrusion into four classes, ranging from low to high. The data for the analysis were obtained from various sources, mainly from hydrogeological databases managed by the Polish Geological Survey. The results show significant heterogeneity in groundwater vulnerability to seawater intrusion in the Polish coastal area. Approximately 807 km² of coastal aquifers were found to be highly vulnerable to seawater flooding, and approximately 496 km² are highly vulnerable due to groundwater extraction. We will also present the concept of improved vulnerability index which is currently developed in the framework of DATASET project (www.datasetw4all.info). The new approach includes vulnerability to salinization and leaching of agricultural pollutants and will be applied to the study area. This research was funded by the Polish Hydrogeological Survey, in the frame work of the task no. 31: Identification of seawater intrusion or saline ascension processes in the coastal zone of Poland. The authors would like to thank the European Commission and NCBR for funding in the frame of the collaborative international consortium DATASET (Groundwater salinization and pollution assessment tool: a holistic approach for coastal areas, Water4All_00084), financed under the 2022 Joint call of the European Partnership 101060874 - Water4All.