Tidal streams have long since been acknowledged as a reliable and predictable source of energy. For tidal energy developments to be economically viable, the arrangement of tidal devices needs to consider regional complex flow conditions. First generation tidal energy development sites are selected on their proximity to port and grid infrastructure, water depth and mean spring current velocity. The layout of tidal energy devices within an array is planned to reduce blade fatigue. The continental shelf seas around the United Kingdom have world leading levels of tidal dissipation; Tidal streaming around the coastline is further accentuated by topographic complexities. The Crown Estate has leased numerous locations around the United Kingdom's shelf seas and a spatially representative selection of these sites has been characterised using the Regional Ocean Modeling System (ROMS). Using the HPC Wales system, high resolution regional 3-D models are developed. Model results enable maps of metrics which illuminate flow features important to tidal energy extraction, which include: tidal phasing, tidal asymmetry and the misalignment of flood and ebb tidal currents. From this assessment four leased tidal development sites within the Pentland Firth are highlighted as the most dynamic of the UK's leased tidal stream sites. Three-dimensional tidal energy extraction techniques are employed within each of the sites in the Pentland Firth which enables a technical resource assessment to be carried out. Furthermore, changing the hydrodynamics has a cumulative impact on natural physical processes of the coastal system. The non-linear nature of the interaction between tidal arrays and physical processes calls for more complex numerical modelling techniques to enable a full quantification of tidal energy development on marine systems.