People taking all-inclusive holidays are paying £100 in hidden costs, a study by foreign exchange specialist Travelex reveals.
Four out of ten British holidaymakers say they are forced to spend an extra £100 or more on all-inclusive breaks.
One in ten people discover they have to pay an extra £200 in surprise costs.
This comes as all-inclusive bookings are 14% higher than this time last year.
Two thirds of people involved in the research said they had chosen an all-inclusive holiday because they were good value for money.
More than 60% said they opted for this type of break specifically because everything would be included.
But they are most often charged extra for food and drink (70%), closely followed by excursions (64%) and souvenirs (49%).
Of those surveyed, 70% think that holiday providers should be more upfront about all-inclusive costs.
A third of those questioned said they had resorted to changing pounds at their hotel, leaving them exposed to poor exchange rates.
The results show that exchange rates at hotels are amongst the worst available.
It found that exchanging £500 at the Marriott Marbella involved a hefty 5% commission, meaning they would only receive €517, against a commission free online order with Travelex which would net €570.
The €53 saving could cover entrance to the Marbella Bahia aquapark for a family of four – with enough left over for snacks.
Elvin Eldić of Travelex said: “With holiday budgets being stretched, given the decline in value of the pound, many families are considering the all-inclusive packages in a bid to keep their holiday spending in check. But it turns out many Brits are getting caught out and having to pay for hidden extras or getting hit with expensive exchange rates in resort.
“It would be easy to forget the need for foreign currency when going all-inclusive, but often when you get to your destination you find that small things, such as taxis, extra food and tips, require cash.”