The volume of goods being ferried across the Irish Sea between Britain and Ireland has collapsed since the UK left the EU.
Road haulage companies say they've changed their routes and are now making huge diversions, shipping between Scotland and Northern Ireland to avoid paperwork in the Republic.
Sky News analysis of several data sets shows trade flows have changed massively since the rules governing trade between the UK and the EU changed on the 31 December 2020.
Where has the rest of trade moved to?
There has been a 208% increase in the volume of freight transported by ferries from France directly to Ireland in February compared to the same month last year, latest data from the ferry operator Stena Line shows.
More goods are now moving between Britain and Belfast because freight can now be sent from Britain to Ireland through Northern Ireland without complex customs procedures.
Ferry data analysed by Sky News shows that freight volumes between Liverpool and Belfast and Cairnryan and Belfast have nearly risen back to their pre-pandemic levels since the start of the year.
However, freight movement between Holyhead and Dublin has halved over the same period. Freight volume has collapsed between Fishguard in Wales and Rosslare in Ireland.
"Freight will always find the path of least resistance. It's a bit like water. It'll always find the easiest way through," said Stephen Carr, Commercial Director at Peel Ports, which operates ports at Liverpool and Heysham.
The company said routes between Britain and Northern Ireland were well above pre-pandemic levels for the first two months of 2021, yet routes between Britain and Ireland were down by more than a third.
Hauliers are increasingly using the port at Cairnryan in Scotland, which is a journey of little over two hours from Belfast on a ferry, to avoid the Dublin-Holyhead route.
But the change to distant ports has left many companies with added transportation costs, compared to journeys previously made to well established and conveniently located ports.
Darren Murphy, managing director of BM Transport, a family-owned haulage firm that sends 150 trailer loads every day across the Irish Sea said the added operational costs are being passed on to the customer.
He said: "You have people like me who are moving freight away from the Dublin to Holyhead route to the Northern Ireland ports because of the customs formalities and whatever else we have to do.
"Obviously that's costing a huge amount of money because of all the extra miles the loads travel, and then the inefficiencies.
"But we have no options. It's simply too much hassle. It's too difficult."
But the industry fears the viability of the Belfast route is likely to be short lived as freight capacity is nearing its limit.
John Martin, policy manager in Northern Ireland for the Road Haulage Association said: "Once the COVID restrictions are lifted and the retail and hospitality sectors open up in Northern Ireland, there will be an increase in demand for products coming from GB into Northern Ireland.
"There will be insufficient capacity on the ferry servicing Northern Ireland because of the increase in the demand from the truck operators in Ireland."
Businesses have had a difficult start to the year and are concerned about what is yet to come.
Under the Brexit deal, Northern Ireland remains part of the EU customs area, effectively moving the border to the Irish Sea. The Northern Ireland Protocol is the agreement managing that process and requires a host of new checks and procedures which are expected to be implemented in October.
This week the European Union launched legal action and accused the UK of breaching international law by unilaterally extending the date the Protocol comes into effect.
Representatives from the hospitality and retail sectors have told a Parliamentary committee that added costs and complexity to trade risks reducing choice and increasing prices for consumers in Northern Ireland, while cutting trade with Great Britain.