Littorina saxatilis and its relatives are model organisms to study adaptation and speciation in natural conditions. The most recent research points towards genomic inversions playing an important role in this process. We have created a high-contiguity assembly using Pacbio long read sequence data, HiC and Illumina short reads and additional assemblies are now available from other groups. We are using these assemblies in comparative genomcs analyses, large-scale (>700 individuals whole-genome re-sequenced) population genetic analyses and analyses of gene expression. These analyses will help to understand the interplay between selective forces, neutral processes and chromosomal rearrangements leading towards local adaptation and speciation.