Holyhead is home to the UK's second biggest roll-on roll-off ferry port in the UK and Gwynedd Shipping, who operate there, say they are "absolutely" not ready for a no deal Brexit.
Andrew Kinsella, Managing Director of the shipping company says the infrastructure they need to avoid a backlog of lorries on the A55 is not in place and it is "implausible" that it will be in time.
Stena Line, the company who manage the port in Holyhead claim they "have taken all prudent steps" to prepare for a no deal Brexit.
Welsh Government have also said in the event of a no-deal, there are likely to be delays at customs but contingency plans are in place to minimise disruption.
Boris Johnson has indicated he wants a deal largely in place by October 11, the day the agenda is set for the European summit on October 18 when the Prime Minister is hoping EU leaders will sign off on an agreement.
Gwynedd Shipping operate at a port in Holyhead and one across the Irish sea in Dublin.
The company employs 150 people and moves about 100 trailers between Holyhead and Ireland everyday - making up about 50% of its business.
In order to deal with the predicted hold-ups in customs in the event of a no-deal, there will need to be space to hold the lorries at Holyhead port.
The Managing Director of the company, Mr Kinsella, says currently there is no such space that can accommodate the vehicles.
More than 600 lorries can be held at the port itself. There are also plans for free spaces at the nearby Road King service station and Parc Cybi.
If that is not enough, a lane on the westbound A55 between junction two and three will be used to stack lorries but Mr Kinsella says the fears of long queues on that stretch of road are "well founded" and not scaremongering.
Whilst Mr Kinsella says he does not think this will make Holyhead unviable, he does think customers may rethink their routes and chose a different port which is better equipped to cope.
I'm concerned for the future of the port, we employ 150 people across Wales, North West Wales, North East Wales, South East Wales. I think the ports of Liverpool and Birkenhead will be better positioned to deal with any customs delays. >
Howard Owen, Transport Manager at Holyhead, says uncertainty surrounding Brexit has been affecting their business this year.
He attributes Brexit as the main cause saying the situation has changed since a year or two ago.
I think all of our customers are afraid. They don't know what's coming. They don't know how to deal with it so everyone's just storing rather than sending goods out.
Gwynedd Shipping has called for more engagement with freight operators from the port run by Stena Line, the local council and called on the Welsh Government for leadership.
However Stena Line say they believe they have adequately prepared.
Their Director, Ian J Hampton, said in a statement that they "have taken all prudent steps to ensure that goods continue to flow as smooth as is practicable, in the event of 'no-deal'."
As a business we believe that we are as prepared as we can be given the backdrop of limited clarity of requirement that the new relationship between the UK and EU will bring, since exit negotiations still continue.
However in Dublin, preparations have been underway since 2018.
Millions of euros have been spent creating T7, which is a new customs and immigration centre in the Irish port.
Charlie Murphy from the Dublin Port Company says they are as ready as they will ever be for Brexit.
We're as ready as we can be. This is a year's long work - last year we started this and got it all prepared. We worked with all the estate agencies who came together to make sure that we would be prepared and what we're saying now is yes, we're ready.
ITV Wales Brexit Correspondent, Carole Green:
The Dublin Port Company told me today it is as prepared as it possibly can be for a no-deal Brexit.
I was given a tour of the port where they have new holding areas for lorries and newly built customs facilities and animal and agricultural sheds are ready for custom checks on food and livestock.
Hundreds of extra custom and immigration staff have already been recruited in Dublin and 20 million euros of investment in the port has been brought forward to prepare for a no-deal.
The port says it is hoping for the best but has planned for the worst.
However, John McGrane of the British and Irish Chamber of Commerce warned that being prepared was not the same as being protected and a no-deal would harm business and communities on both sides of the Irish Sea.
He told me his Welsh members, particularly freight operators are nervous about the impact of any checks and customs delays disrupting trade routes.
New ferry routes directly from Ireland to the European mainland are up and running and there is confidence on this side of the Irish Sea these routes will only grow in popularity.
That is a worry for Holyhead - although the Welsh land bridge route is quicker now - delays could take the edge off its competitiveness.
International shipping is mobile and customers to and from Europe now have more choice through Dublin.
It was Budget Day in Ireland today and 1.6 billion euros was committed to help Irish businesses cope with a no-deal. There are concerns here too of the economic impact if talks break down and the UK crashes out.