Ocean ice capable of impacting marine operations occurs periodically in the most favorable sites for energy harvest from the tidal currents of the Bay of Fundy in Nova Scotia and New Brunswick. In-stream tidal current harvesting devices deployed at these sites should to be engineered to tolerate at least 30% ice cover with 15 cm (6 inch) thick floes at least 100 metres in length. Propelled by tidal currents and prevailing winds, ice floes may achieve velocities in excess of 8 knots in some locations. In very severe winters, in-stream tidal current harvesting devices may be subjected to periods of 90% cover of rapidly moving or packed ice thicker than 30 cm (12 inches). Markets for ice-tolerant tidal current harvesting devices developed under the moderate ice conditions in the headwaters of the Bay of Fundy may exist in other jurisdictions with energetic tidal flows which experience more severe conditions of ocean ice.