Stena Mersey operates the Belfast - Birkenhead service for Stena Line back to back with sister vessel Stena Lagan. Built as Mersey Viking in 2005 by Cantiere Navale Visentini for Levantina Trasporti of Italy. Registered in Bari the vessel was chartered to Norse Merchant Ferries for their Belfast - Birkenhead service. The Mersey Viking was later to see a number of company changes. Norse Merchant Ferries were bought over by Norfolkline, in 2010 came the acquisition by DFDS. Mersey Viking shortly after was renamed Mersey Seaways. Later in 2010 Stena Line purchased the DFDS operation from Belfast and the vessel was renamed Stena Mersey in 2011. In 2012 Stena bought the vessel outright from its charter and later re registered to Belfast under the UK Flag.