Without sustainable offshore aquaculture it is impossible to achieve food securityfor coastal communities. Growing populations in coastal zones, amounting toapproximately 40% of the entire human population, exert high pressure on coastalecosystems and natural resources, and furthermore increase the need foradditional food sources. In coastal zones, marine-based nutrients offer greatpotential to meet this demand. With sustainability in mind, extractive species likemussels and oysters, which require no additional food, are becoming increasinglymore important. Therefore, researchers, industry representatives, andpolicymakers alike are seeking to utilize offshore areas for shellfish aquaculture.To successfully grow shellfish in offshore areas, it is vital to understand thecomplex interaction of offshore aquaculture systems with waves and currents.Modelling these interactions facilitates the development of aquaculture structuresthat can withstand these high-energy environments. Therefore, the aim of thisthesis is to increase the understanding of the complex flow around offshoreshellfish aquaculture systems and their interaction with waves and currents. Theliterature review reports on the hydromechanic drivers with a focus on the forces,motion, and wave-structure interaction of bivalve aquaculture systems to lay asound basis for the analysis and interpretation of the results. From there, a lack ofinformation regarding the motions and forces of bivalve aquaculture componentsin steady and oscillatory flow as well as a lack of guidance as to how the complexsurface of mussel dropper lines should be modelled is identified. To address thesegaps of knowledge, physical experiments with live blue mussels (Mytilus edulis),substitute surrogate models, a newly designed aquaculture system, and naturallyfloating islands were conducted. The results of these experiments, published infour journal manuscripts, provide insights regarding the hydrodynamiccoefficients for mussel dropper lines and its influencing parameters. Furthermore,the procedural design and creation as well as the hydrodynamic fit of a surrogatestructure are shown. Wave and current tests with the novel aquaculture systemand the comprehensive analysis of the hydrodynamic interaction of waves andfloating natural islands in a large-scale facility provide insights regarding themotion and forces. Combined, the results enhance the understanding of thehydrodynamic processes around bivalve offshore aquaculture structures.