Genomic resources generated for different evolutionary genomic projects on the marine intertidal snail Littorina saxatilis by research groups from University of Gothenburg in Sweden and The University of Sheffield in the United Kingdom. The dataset includes a de-novo whole genome sequencing assembly of one individual and pool-seq genome re-sequencing of several samples. The rough periwinkle, Littorina saxatilis, is a coastal gastropod mollusc very common throughout northern Atlantic, and an excellent model for the study of local adaptation and speciation. In Spain, UK, Sweden and other areas, snails are locally adapted to different environmental conditions despite a continuous distribution over a contact zone. The observed local adaptation and divergence seem to have occurred multiple times in parallel. The overarching goal of our research is to unravel the evolutionary drivers and genomic basis of parallel divergence and local adaptation in L. saxatilis