Being hit by fees you weren't aware of while on vacation is one of the worst feelings - whether it's for checking an overweight bag or shelling out for internet use at the hotel.
This week, the Global Business Travel Association (GBTA) released a list which could help travelers this summer, compiling ten of the hardest-to-track travel fees that affect its business traveler members and those on the move more generally.
The most problematic fees, the GBTA concluded, were those which were common but unpredictable and difficult to budget for and record, making keeping track of those travel expenses much tougher than it needed to be.
Perhaps unsurprisingly, four of the top ten were changed by airlines, including expenses for soft drinks, buying or renting a headset to watch the entertainment, buying movies or videos or buying food.
Luggage fees weren't included as they're typically noticeable upfront -- you'll know if you have to pay them -- but all the others many travelers wouldn't be aware of.
When it comes to hotels, travelers should be aware of fees for internet use and also for car park usage, which are normally added onto the bill at the end of a stay for a nasty surprise, as hotels often charge over the odds for both.
Car rental is also full of troublesome charges, said the GBTA, with toll passage, late returns and dropping off a one-way rental all making the top ten.
The final sneaky bill was fuel, which most drivers should be aware of but still manages to catch many out -- return your car anything less than 100 percent full, and you'll normally be whacked with the cost of refilling it at a considerable premium to the basic fuel costs.