This was really fun to look up, one of my first jobs was as a camp counselor for the town I grew up in. While I have no kids myself, I could totally picture my previous campers having an absolute blast and not being bored all summer long! Come to think of it, I could see my friends doing some of these and they are supposed to be adults.
I incorporated activities that are active and passive as well as things the kids can do inside or outside depending on the weather. And if you run through this list there are plenty more where they came from – check out all of the ideas, there is a special one at the end that I think every parent/guardian would love!