After the recent cancellation of Stena Line's Dún Laoghaire to Holyhead service over the Christmas period, it is now thought that the ferry operator could be considering completely pulling out of the harbour.
It is understood that Stena and Dún Laoghaire Harbour are in negotiations over the future of the service.
The Irish Times reports that neither side will comment on the finances of the deal, as they say that the information is "commercially sensitive".
Stena already operate a route between Dublin Port and Holyhead. Located just 14km north of Dún Laoghaire, the port could absorb traffic if the south Dublin service is withdrawn.
Dún Laoghaire to Holyhead sailings normally run through the summer, and over the busy Christmas period.
When the the company announced that this year's festive service had been dropped it cited, "commercial and operational reasons".
Stena is believed to be Dún Laoghaire Harbour's biggest customer. The company have recently indicated its plans to try and attract more cruise traffic.
These boats generally dock in Dublin Port and the harbour is arguing that it is better suited to tourist traffic.
The Stena plan to attract more traffic is being backed by Dún Laoghaire Rathdown County Council and the Dún Laoghaire Business Improvement Group. The harbour company is planning to spend €15m building a special berth for cruise traffic.
Some 23 cruise ships are expected to bring 66,867 passengers to Dún Laoghaire in 2015.