BBC passenger Chris Clotworthy, who had been traveling home from Glasgow, said code words were announced over the ship intercom.
He said: "The boat did a complete 180 degree turn and looked to be heading back to Scotland, this was when it was level with Blackhead (in County Antrim).
It then did another complete 180 and stopped."Mr Clotworthy said people were "relatively calm".For more stories from where you live, visit InYourArea. .
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