Fresh submarine groundwater discharge (SGD) and seawater intrusion (SWI) are complementary processes at the interface of coastal groundwater and oceans. Multiple common drivers enable or limit SGD and SWI. However, we find that SGD and SWI are rarely studied simultaneously. In this meta-analysis, we synthesize 1298 publications, examining drivers of SGD and SWI, where and why they are studied, and at which scales they are impacted by their drivers. Studies of SGD and SWI accumulate in urban coastal basins with high gross domestic product (GDP), and high permeabilities, where measurable groundwater fluxes are expected. We find, that studies investigate various drivers, but rarely assess the scales they act at. Effects of temporally recurring processes (e.g., tides) are studied more often and are better known than effects of spatial variability (e.g., permeability). Future studies should investigate SGD and SWI simultaneously, report impact scales of drivers explicitly and explore unchartered coastlines.