There is good tech these days with cameras with audio. Install them and door/window alarms.
I’m also in the camp of don’t take eyes off children like this. I knew a family who lost their preschool school son to an accidental drowning. He managed to unlock a bolted door, climbed a fence, and went into a neighbor’s pool. Supervise, supervise, supervise. If you need to do something else, get a sitter.
Sounds like climbing is something he enjoys. Can they get appropriate things to climb? A child rock wall? Slides to climb, a tree house, etc.
Is he getting enough outdoor time? If he just LOVES outdoor time can they increase that time?
An alarm system that will alert when any doors are open is a good idea. Our is that way - the alarm doesn’t have to be set for the doors to make “noise”.
Also 2 years is not too young for some natural logical consequences that he can understand.
Yes, he can climb out of her yard or mine. He can manage to shimmy up my gate and open the latch pr can climb my 5’/6’ fence, but rarely does. He can climb countertops, he can climb the refrigerator, he will climb a four drawer metal file cabinet he does stuff most of us would simply not think to do. He can hop over her 42" small yard fence (they are on property so there is a ring of shorter fencing around the house and he does this way too often as he is fascinated by the neighbor and wants to go there all the time. They have been fighting it for months. That is something to be addressed, I mean beyond the current constant surveillance. I do have cameras at my home as it is multi-level and you just cannot possibly see everyone all the time, so I watch the playroom via the camera.
They do childproof, but are constantly having to adapt and adjust as he is more and more able. I was hoping for some ideas on how to teach/discipline him to not climb the fence or not to leave the yard. They are not 100% against spanking but feel like it might engender an “I’ll show you attitude” instead of convincing him not to leave the yard. Their other kid is super busy and active, but not with the same risk-taking behaviour.
They are lucky to have a home with a full covered porch, all the way around, on rainy days, porch laps are a thing, as is riding bikes around and around the porch and, yes, the boys adore being outside and are outside all the time, with a lovely fenced area around the house, larger than many suburban yards and with both groomed and wild areas that a guy can dig and climb trees etc. It’s pretty perfect, but he still climbs out.
I think the best description of this kid is, “boy can do ANYTHING he sets his mind to” and only a few parents hear the veiled desperation in that comment 
But when you meet someone who has had one, they immediately know what you mean. I look forward to seeing his energy and drive channeled into a lifelong passion.
Maybe he’ll end up like my middle kid (whom we referred to as “Disaster Boy” when he was little), whose passion for helping people blows me away. He is doing great things. It was a rough ride until he found his passion, though!
Harness while outside. Natural consequence is, “When you agree not to climb, I’ll take the harness off.” Take it off and be ready to run after him. Repeat until he actually does not climb, but do not take your eyes off him!
100% spanking doesn’t work. Saw it with my brother (who was the wild child in our bunch- which was great help for me in trusting that my one would indeed grow through this!)
Just say no to spanking. No one feels good about that when it happens in a household.
Does he have other behavior management issues? Other defying? How are his language skills? Is he just 2 or a close to 3 year old?
My youngest son was a bit like this. We channeled his daredevil behavior into playing hockey (started at 5, but 3 yesr olds were learning to skate in his program)
Until he gets a little older there really is no substitute for constant presence with him. You cannot leave him alone. Intervention and redirection are needed before he accomplishes his escape, climbs where he shouldn’t or any other of his risky activities. Redirection to acceptable large motor activities are your best solution. Have play equipment involving climbing. Play soccer, play tag, play catch. . It’s summer have water. Go for walks with the harness at his pace to pick up leaves, look at bugs. I had 3 boys. They can be exhausting.
Honestly, this thread is triggering to me! I understand the children for whom no amount of redirection works. Sure, you can intervene but they will be planning to get right back to it in an hour, a day, a week, a month. Just as soon as possible. They don’t give up. Ever. That’s why we lock them up when we can’t be close enough to grab them.
Thirty something years out, much older and wiser, I still wonder what might have worked better in terms of discipline. “No” to corporal punishment, because they are stubborn and it doesn’t teach them what the real problem is: that the activity is dangerous to them. At age two to three, mine charmingly conceded some rules might make sense for some adults but not necessarily for children. For a toddler a time out works as an immediate consequence, for specific unacceptable behaviors, but doesn’t work for some behaviors and tendencies you describe. You can’t think of all the things you have to warn them not to do, and there is, of course, the fear if you try, you just open up new possibilities. imho.
What I did do: tell cautionary tales (trying not to be too scary) and eventually they had developed enough conscience they were sometimes willing to behave to spare my feelings. To this day, I may say “that really really worries me and makes me upset” Think of all the fairy tales where children that wander get into trouble. They exist for a reason. It’s a tight rope. Perseverance and drive are such excellent qualities to foster and encourage.
Showing them smushed road kill surely wasn’t the best parenting technique, but I was pretty much at my wit’s end and scared out of my mind. It was difficult to see it made an impression. There’s so much magical thinking in the very early years. They just can’t understand consequences.
I really think you have to just accept keeping them safe till they gain some common sense is the priority, focus on that task, and wait for them to outgrow it.
Even before this thread, when I got bored in at my shelter in place empty nest house these past months, I’d just imagine those years. It was the most fun I ever had, but I will never recover from the stress. Sometimes I still have nightmares about narrow escapes.
Really, the most practical suggestion I have is to hire a childcare helper, if that is financially feasible. It’s one more pair of eyes, and helps spread out the stress.
That’s what they were thinking, too, about spanking. They don’t spank and figured, hey if it saved his life or his body from major injury, it would be worth it, but it likely would backfire. And like a dog that won’t come, you can’t smack it when it does finally come or when you catch it, or it will never come back.
He is a bit closer to three than two. He is a bit defiant, in terms of dumping a basket of toys, etc., He’s got very deep feelings, sad., mad, glad, happy, he feels everything deeply But the safety issue is mostly the escaping and climbing the split second anyone turns their back. Like she put a bolt onto the pantry after finding him on the top shelf, 6’ above the tile floor, eating chocolate chips, when she’d literally left them eating lunch for 20-30 seconds to grab something from the other room. His Mom and Dad are fantastic parents, really great, just seeking more creative ideas.
If he is closer to three he can start grasping the benefits or negatives of natural, logical consequences - if his other development - specifically expressive and receptive language are typical of an almost 3 year old.
This book was a game-changer for me with my one: Raising Your Spirited Child: A Guide for Parents Whose Child Is More Intense, Sensitive, Perceptive, Persistent, and Energetic*. Her follow up book (Kids, Parents, and Power Struggles : Winning for a Lifetime) is every bit as good.
*when she was coming up to 6, and I didn’t realize how much she could read, it was out on the kitchen counter to lend to a friend- she picked it up, read the title out loud, and said ‘hey mom, this is like me!’. LOL no kidding, baby, no kidding…
Re: spanking:
I have done it. Not sure how much it helped, and I certainly didn’t feel good about it. My dad still occasionally talks about one time he spanked me when I was 3 of 4 and how bad he still feels. I am 48. Also both my sister and her daughter were spanked to no avail. I’m pretty sure when they were being defiant you could knock them unconscious and when they came to they would reply with “that all you got? Didn’t hurt.” Some personalities are immune to it.
Possibly helpful advice:
We did eyehook latch on bedroom door with D25 when we found her in the garage at 3 am one morning.
I’m sure you have seen people put a stick down to “lock” a sliding door. That won’t help here, but what about a tension curtain rod high enough that he can’t reach it?
I have a friend that had teen foster kids for several years, many of which were runners. All of her doors and windows had alarms. Giving him a 30 second headstart is a lot better than finding out he left 20 minutes ago.
What about something with GPS? I use Tiles all the time, but I don’t think they would be useful here due to limited range. I’m guessing there is something helpful, I think there is something you can carry if you are going to avalanche prone areas. An old cell phone would work, but probably too bulky to keep on him. It looks like on Amazon there are keychains with over 100 ft range. I’m guessing a bit of research with this would be helpful.
Funny @dadof4kids i’d sent her some links to dog collar GPS alerts a few weeks ago. If only an ankle bracelet with GPS could be put on! The curtain rod on the slider is a great idea.
So many of these ideas may be helpful and work for the family!
But…
Agreed, @abasket, and Mom and Dad are quite diligent, but, hey, what if older brother throws up and you turn your back to catch it, or any of a number of other times when you might take your eyes off him for a few seconds. So, here to the CC pool of experience to make sure no stone is unturned in terms of both safety ideas and intervention ideas.
OP, I had one of these. He would climb almost anything.
I didn’t go public places where he couldn’t be safe (in the cart, in a leash). So we stayed home a lot. I wore a backpack carrier with him in it while I mowed the yard if DH wasn’t home. I sometimes used the tether in the yard, honestly, to keep him where I could see him (clip an end to me, an end to him. He usually tried first to unclip it)
You really need to see it as a safety issue. Thinking of it as “running in traffic” helped me reframe it. So we established hard boundaries. Violations got time outs, and yes, early on the whole day was policing and time out! After establishing that Mom and Dad were serious, we moved to “a good day earns a trip to the playground” with the giant climbing thing.
It isn’t funny, so no reinforcing it with smiles and shaking the head. Some things are not for climbing, non negotiably. Again, it’s a safety issue. But do wear him out! get him a mini trampoline, a bouncy horse, a pogo stick when he’s older (mine had several, he would just bounce forever) a rope ladder, a zipline, homemade obstacle course…
Safety issue. Not a character flaw, will someday be handy, but now, it is a safety issue
I am trying to think what type of professional might be consulted. I imagine some parents take a kid like this to a child psychiatrist and consider some sort of medication. To be clear, I am not suggesting that. I know from personal experience what this kind of vigilance takes out of a parent. I wonder if anyone has had a helpful experience from a professional, and what kind of professional.
I think ‘village’ more than professional. Extra hands- neighbor kid too young to babysit who comes over to ‘play’ for pay while you are home, swapping times with other families with high octane kids,etc makes a big difference.
Mostly, knowing that although this season feels infinitely long, it does pass. These kids so often turn out to have amazing gifts as they learn to channel all that curiosity & energy. Keep looking for the positive, even in the exhaustion- it’s there!