Littorina saxatilis is a model organism to study speciation in natural conditions. The most recent research points that genomic inversion play an important role in this process. Yet, a good genome assembly is still missing for this species. The aim of this project is to produce such assembly using both Pacbio long reads sequence data and Illumina small reads. This will help understand how the interplay between selective forces, neutral processes and chromosomal rearrangements could lead to speciation.