I am just now taking my kids tent camping and they will be 5 1/2 and 7 1/2. I COULD NOT have handled it any sooner.
Some kids would be awesome to take. My one friends two year old is so mellow. He is happy to hang out on her hip or stuck to her leg. He doesn't fuss or cry...etc. He is a joy to take anywhere!!!
My kids would not have done well. I couldn't take them to a friend's house because they would find the ONLY thing that was a choking hazard in the whole house and put it in their mouths!
They both crawled before they were six months old and walked by nine months. I was chasing toddlers and keeping them outta trouble for 5 solid years since they were two years apart and it took till the youngest was 3 to be able to trust them enough to not watch them constantly.
Tent camping is a lot of work just to set up your site and keep everything going with limited resources... add to that having to hawkeye little kids to keep them safe and I wouldn't have enjoyed the time at all!
I did rent cabins at the local state park within driving distance of my house so that we could get them used to all those things that you have to start them on young:
1. Fire ashes on your food
2. Not rubbing your eyes with bug spray on your hands
3. Groping around blindly in the dark when the lantern runs out.
You know... all that stuff that makes camping, camping, and not just moving your house into the woods for a visit!!!
