A boat which sails between Dublin and Wales has had to expand its onboard shopping due to high demand.
A ticket costs €16 return for a foot passenger, with up to 40% duty free savings on drink, cigarettes and perfume.
Henry McKean jumped onboard the Stena Line Estrid, and told Moncrieff some people didn't even get off the boat.
"If you're travelling to the UK you can take 42 litres of beer, or you can also take four litres of spirits and you can take 200 cigarettes," he said.
"If you're travelling to Ireland, not as much: 16 litres of beer, plus one litre of spirits and 200 cigarettes.
"Any other goods - €430 worth of cosmetics, that's travelling to Ireland - and travelling to the UK when it comes to cosmetics it's €390.
"They'll tell you how much in the duty free you can buy - and these prices are in sterling.
"So add an extra 15% when we're talking in sterling here, that's the exchange rate".
'You save at least 40%'
Henry spoke to some customers shopping on the high seas.
"I was here in September and I got even more stuff, perfumes and aftershaves," one man said.
"I might get some more aftershave on the way back; but you save at least 40%.
"The fare was only £12," he added.
Another shopper told Henry: "I got a bottle of Baileys, which is £12 a litre, I bought a bottle of [aftershave].
"I got 400 cigarettes," he said quietly.
"I bought my wife a nice bottle of Chanel Coco, which the girl in there recommended," he added.
Another shopper said: "I got two bottles of gin [for] £26".
One man told Henry: "In Ireland the price of these products is sky high, though the roof, at the moment.
"So to be honest it's amazing value that I'm getting on the ship", he added.
'It never stops'
Simon Palmer from Stena Line said the boat sails every day, almost.
"We are onboard the Stena Estrid, which is one of newest vessels," he said.
"It was launched in 2020 and it does a return trip to Dublin - it never stops, apart from Christmas Day".
He said they have had to expand the shops such is the demand.
"It's one of the bright spots of Brexit, the only bright spot," he said.
"We're dealing with a lot of Brexit issues, but the duty free aspect has been a good thing to deal with.
"We now have more retail space on the Irish Sea than any other ferry company.
"We've actually had to extend the shops onboard this vessel... it's because of the demand for duty free".
The boat even has a kennel room, for people to take their dogs with them.