Provided whatever valuables you brought on vacation are small enough to fit in the miniature safe in your hotel room, it's kind of assumed that once they're in there, they'll be... y'know, safe. If the above video by cyber security expert Jim Stickley is to be believed, though, that safe's way easier to crack than we'd like to think.
As Stickley demonstrates, certain models of hotel safe have a "backdoor" that allows potential thieves to circumvent the numeric keypad and break in with the standard lock-picking tools they'd use on a traditional door lock. The ease with which he's able to crack the locked safe is unsettling, especially once he seals it back up as though nothing ever happened.
Now, the video leaves us with an important question: do all hotel room safes have this same security flaw? Probably not, since a cursory Google search nets you scores of images of safes without the "backdoor" Stickley uses to gain access. However, a few of them do appear to have similar designs, which seems to indicate the same trick would work on them.