P-and-O Ferries has resumed a full service from Northern Ireland to Scotland.
The Larne to Cairnryan route was interrupted in recent weeks following a public backlash, from the company's sacking of 800 workers without notice last month.
They were replaced with cheaper agency staff.
The European Highlander ferry - one of two which operate on the Irish Sea route - was subjected to an inspection by the Maritime and Coastguard Agency.
