Fig. 1: Map of the study site in the Fall of Warness, Orkney, Scotland, UK.

A Overview map showing the location of Orkney off Scotland's mainland, highlighted by a red box. B Location of the Fall of Warness managed by EMEC, highlighted by a red box. C Map of the Fall of Warness coloured by bathymetry showing the mean location of the O2 (59°8.664’N, 2°48.935’W), representative ebb tide fine-scale (14/04/2022, T6) and broad-scale (15/04/2022, T7) transect line data, respectively, as well as an upstream aerial drone hover used in particle image velocimetry (PIV), to scale. The (x,y) axis corresponds to the local coordinate system used in this study. D Aerial drone shot of the idled O2 floating tidal turbine (hull/body overall length = 74 m) deployed in the Fall of Warness taken on 14/04/2022 during peak ebb tidal flows (note, while the turbine was not generating, the rotors were submerged in the operating position). E Streamwise depth-averaged velocities extracted from O2 hull-mounted ADCPs highlighting survey periods during the fine-scale (red) and the broad-scale (orange) transects, respectively. Velocities are aligned with the local coordinate system, with positive values on the flood tide. Instruments were not  recording during the night of the 13th/14th. F Overall excursion (in metres) of the O2 during the sampling period. Bathymetry:© British Crown and OceanWise, 2024. All rights reserved. Licence No. EK001-20180802. Not to be used for Navigation. Boundary-Line™ shape files updated in 2022 using EDINA Digimap Ordnance Survey Service. Source data for E&F are provided.