What is One thing no one tells you about family vacation with young kids?

When you have young kids and you go on a beach vacation, somewhere nice, you don't actually get any vacation time. You have to constantly watch your kids from falling into the ocean, or jumping off a balcony, or eating lots of sand. Real family vacations where you can relax don't start till much later when your kids are finally playing on their own for longer than 2 minutes.