Natural analogues studies have received growing interest during preceding years in a CCS perspective. There is a strong willing to deploy robust and reliable technologies to ensure the safety and integrity of CO2 underground storages. Here we present a dataset acquired in the Eifel volcanic district, using geochemical monitoring methods focussing on both dissolved and gaseous species. Onshore and offshore monitoring (Lake Laacher See) were performed to depict spatial behaviour of CO2 natural releases. Additional gaseous species, mainly helium and radon, were also monitored to better assess the shapes of gas vents, using methodologies that were learned from hydrological and tectonic applications. Lake water monitoring allowed the characterisation of the water body itself, in terms of lateral heterogeneities, to evaluate the impact of CO2 deep degassing near the bottom of the lake. The use of a dedicated sensor for monitoring in situ CO2 partial pressure did not provide more valuable information that was learned from more classical physico-chemical parameters. From those investigations, the usefulness of geochemical monitoring is still demonstrated, but the use of complementary approaches and methods is still needed to get a powerful set of techniques able to warn in case of leakages occurring from depth.