“Land and freshwater molluscs of Northern Spain” is an occurrence dataset containing 222 observations of 73 different taxa of land and freshwater molluscs encountered in Northern Spain (Vízcaya, Cantabria and Asturias). Various sites were inspected in a period between 2004 to 2019. The aim is to contribute to the knowledge on the ecology and distribution of these species such that it may aid conservation and research of these organisms in the future. The dataset is published as a standardized Darwin Core Archive and includes for each observation a stable occurrenceID, scientific name, date, and location of the observation, as well as info on lifeStage and organismQuantity, and supplementary remarks on the determination and the observation itself. We have released this dataset to the public domain under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication (https://creativecommons.org/publicdomain/zero/1.0/).