The value of the pound has plunged to close to parity with the US dollar for travellers using airport foreign exchange bureaux.
Travellers at some UK airports are barely being offered one dollar for each of their pounds, following a month of Brexit uncertainty, the BBC reported.
Those exchanging pounds at Heathrow are being handed back as little as $1.05.
The pound has fallen by 11.77% against the US dollar since mid-April.
In some places, sterling buys less than a euro, with tourists being offered just 92 cents for every pound.
The pound is now at its weakest against the dollar since April 2017, although it has recovered slightly since prime minister Theresa May won her vote of confidence.
The pound was briefly worth more than $2.00 a decade ago.
Ian Strafford-Taylor, chief executive of currency traders FairFx, told the BBC: “Over the last couple of months we’ve seen several developments in Brexit negotiations, MP resignations and more recently a leadership challenge which have all sparked significant turbulence for the pound.
“It remains to be seen how things will play out as we head towards the UK’s exit from the EU, but we are facing even more uncertainty, and uncertainty is one of the biggest causes of volatility for currency.
“Amongst all the chaos, people should stay alert to the political landscape to give them the best chance of buying their holiday currency when the pound is strong.”
However, turbulence in currency markets is being seized upon by P&O Cruises by issuing a ‘Brexit promise’.
The line is emphasising that passengers pay with pounds on board, thereby avoiding currency fluctuations.
President Paul Ludlow said: “We want to reassure our guests that whatever is happening in the world of politics, their holiday and peace of mind is of the utmost important to us.
“Our Brexit promise is that no matter what the future brings, our guests can rest assured when booking a P&O Cruises holiday as they will always pay in pounds sterling in advance and can take advantage of a low deposit to secure their holiday.
“With sailings directly from Southampton and, by choosing shore excursions in advance, our guests can explore Europe without the need for euros.
“In addition, the currency on the ships is pounds which covers all shopping, dining, drinks, indulgent treatments in the spa and a range of shops.”