Footage of the P&O European Highlander departing for Scotland
The P&O European Highlander returned to service on Sunday afternoon for the first time since the company sacked 800 staff on St Patrick's Day.
The ferry had been prevented from sailing by the Maritime and Coastguard Agency over safety concerns.
It departed from Larne at midday.
The sailings today mean both P&O vessels are back in action on the Larne to Cairnryan route.
Stena Line's extra freight ferry, brought on to ease congestion, will make its final sailing from Belfast to Cairnryan tomorrow.