This paper examines cave environments as unique spaces of knowledge production and shows how visualizations of natural cavities in maps came to be powerful tools in scientific reasoning. Faced with the challenge of limited vision, mapmakers combined empiricism and imagination in an experimental setting and developed specific translation strategies to deal with the uncertain origin of underground objects and the shifting boundaries between the known and the unknown. By deconstructing this type of cartographic representation, which has barely been studied, this (...) paper furnishes surprising insights into the scholarly practices and tools used to deal with this considerable epistemic uncertainty and to signal credibility and trust to potential users. The array of maps used for this study includes both archival and published sources, depicting caves in Europe, America and Siberia. (shrink)