Replacing it is the brand-new 5,200-passenger ship Iona and an as of yet unnamed vessel.
Carried out in conjunction with conservation charity ORCA, it's part of a larger effort to monitor the Irish Sea's marine life.
Guests won't have to pay the £7 a day from May 2019.
The improvements will allow it to accomodate P&O Cruises new ship Iona when it launches in 2020.
The public voted them Best Ferry/Minicruise Operator and Best Ferry Booking Website.
19 new stores will be opened across 15 P&O ships.
Sail between Cairnryan and Larne and take your Caravan for FREE when travelling on a midweek ferry. Book by 18th December 2019.