The results of demonstration tests of a full-scale hydrokinetic turbine for river and tidal sites, are presented at the conclusion of the EU-funded CRIMSON project. The turbine features a 3-bladed crossflow, 9.0 m2 capture area rotor, representing one module of the ORPC RivGen© technology. A comprehensive matrix of operational trials was performed to characterize the turbine hydrodynamic performance and the efficiency of the power conversion system. An advanced blade structural monitoring system based on fiber-optics strain sensors was implemented and validated. The full-scale turbine tests were carried out at the hydrodynamics testing infrastructure at the Institute of Marine Engineering of the National Research Council (CNR-INM). This facility, among the largest of its kind globally, provided fully controlled and repeatable conditions that allowed to deliver a high-quality dataset on system performance and reliability, contributing to develope new knowledge for the enhancement of hydrokinetic turbine technology. The results allow ORPC to characterize the strain profile precisely over a rotation and to identify the maximum/minimum strain experienced by the foil for every flow condition tested.