The article explores medieval perceptions of the caves of the Kyiv-Pechersk Lavra through the lens of symbolic thought that dominated Christian culture in the Middle Ages. It argues that modern positivist approaches—focused on geology, measurements, and physical structure—are insufficient for understanding the caves’ original spiritual and cultural meanings. Instead, the study emphasizes the symbolic association between the cave space and the water element, even though water is physically absent from the Lavra caves.In medieval consciousness, the visible world was perceived as a signbearing reality pointing beyond itself. Within this framework, the caves were not understood merely as underground corridors but as liminal spaces analogous to rivers or seas—places of passage, purification, initiation, and transition between worlds. Drawing on hagiographic narratives, the Kyiv-Pechersk Patericon, archaeological evidence, and early modern descriptions of Kyiv, the article demonstrates that water (particularly the Dnipro River, as well as the sea and subterranean waters) and the caves were often perceived as semantically eq uivalent sacred loci.Special attention is paid to burial practices in wooden logs discovered in the Lavra caves. These coffins are interpreted symbolically as boats carrying the soul across a mystical river toward the heavenly shore, while the cave corridors themselves are understood as winding underground rivers. This imagery reflects ancient and Christianized conceptions of death as a crossing and of burial as participation in Christ’ s death and Resurrection.The article also examines medieval and early modern accounts emphasizing the extraordinary length of the Lavra caves. Such descriptions are interpreted not as factual measurements but as expressions of an existential experience of boundlessness, consistent with the symbolic identification of the caves with vast underground rivers or seas. Poetic interpretations, particularly those of Sebastian Fabian Klonowic, are shown to preserve a mythopoetic vision of caves as the dried beds of vanished subterranean rivers—spaces formed by water and sanctified by its absence.In conclusion, the article argues that during the Middle Ages the caves of the Kyiv-Pechersk Lavra were understood as a sacred, “post-water” space shaped by the symbolism of the water element. Whether explicitly or implicitly, water functioned as a key symbol linking natural formation, mythological imagery, and Christian theology of purification, passage, death, and eternal life. Only by moving beyond positivist frameworks can the caves be fully understood as carriers of meaning within medieval symbolic geography.