ADCP transects have used to characterise tidal stream resources in the Ramsey Sound area of Pembrokeshire, UK. Previous resource assessments have previously suggested that this area is one of the most promising for tidal stream deployments in the UK and this contribution confirms the commercial viability of the area. In this study three channels were considered: Ramsey Sound itself and two channels to the west formed by small offshore islands. Current velocities were used to compute the tidal energy flux through the channels. Maximum instantaneous peak flux through the three channels ranges from 180 MW to 70 MW. Flux cross-sections are presented and the impact of meso-scale bathymetric features on flux and on the cross-transect variation of maximum flux over the tidal cycle is described and discussed. Theoretical values of extractable power potential are calculated and range between 7.2 MW and 21.8 MW. These values are approximately 1/4 of the average flux through the measured cross-section. One channel is identified as being preferable for the first stage of array deployments given greatest homogeneity of flux through the channel cross-section and it having the highest power potential. (C) 2013 Elsevier Ltd. All rights reserved.