Lake Lednica, Greater Poland, is one of Poland’s most important and longest-studied underwater archaeological sites. The residential centre established on an island was one of the central points in the state of the first Piasts. Previous research located two bridges to the island and discovered the largest collection of early medieval military objects in Central Europe in the lake. In the 2017 season, a third bridge was discovered on Lake Lednica leading to the small island called Ledniczka on which the layers of an early medieval settlement and clear remnants of a motte-type medieval structure are found. Three seasons of research on relics of the crossing suggest that it may have functioned in two periods: in the tenth century and at the turn of the fourteenth century. During the research, a number of military items, pottery, objects made of organic materials and fishing tools were found. and Lednické jezero ve Velkopolsku patří k nejdůležitějším a nejdéle studovaným lokalitám podvodní archeologie ve střední Evropě. Rezidenční centrum zřízené na zdejším Lednickém ostrově bylo jedním z hlavních míst prvních Piastovců. Předchozí výzkum odhalil dva mosty spojující ostrov s pevninou a největší soubor militárií ze dna středoevropského jezera. V roce 2017 byl identifikován další most, tentokrát zpřístupňující ostrůvek zvaný Ledniczka. Další výzkum ukázal, že most pravděpodobně fungoval ve dvou periodách: v 10. století a na přelomu 13. a 14. století. Přinesl také početný soubor militárií, keramiky, rybářského náčiní a výrobků z organických materiálů. Na ostrůvku byly dokumentovány raně středověké situace a opevnění typu motte.
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.