UK operator P&O Ferries has said it carried more freight on its Larne-Cairnryan route last year than at any time since 2011.
Volumes reached 210,533 lorries and trailers, up 1.3% on 2016.
It runs two ships on the service between Scotland and Northern Ireland.
Neal Mernock, P&O Ferries' sector director for the Irish Sea, said: "These outstanding volumes illustrate the vital importance of our service to the thousands of businesse and millions of consumers who rely on the efficient and reliable transportation of goods across the Irish Sea."
