The temporary lowering of the water level in Dalešice Reservoir for maintenance in the autumn of 2021 created an opportunity to conduct an archaeological investigation of the Kramolín hillfort – a site permanently flooded since the 1970s. A small group of archaeologists reached the shore of Kramolín island by boat and performed the survey with metal detectors and GPS hand held devices. This survey produced a large collection of lithic artefacts, pottery sherds, and isolated metal artefacts from different prehistoric periods (including the Neolithic, Eneolithic, Bronze Age, Iron Age, Roman period and Early Middle Ages), which had already been identified during previous excavations. However, although the site was illegally surveyed with metal detectors earlier, several important artefacts were still found. In addition, the current state of the overlying sediment and its erosion was documented. The survey showed that the site is not yet exhausted and repeated survey in the case of the lowered water level can again provide more important information about this site.