Hello From Soaking Wet Working Mother

There really isn't any better safety (aside from an autocover) than a separately fenced pool. I do agree that a fence around the pool would be great. I would go with aluminum and not wrought iron though. Iron will need recurring maintenance over time.

I might suggest in the bigger picture, looking at potentially removing the deck and instead, installing a small landing outside of the slider, then wide steps down to Level 2 which would now be a large space. That would create a more wide open and usable area on Level 2. Then you would build a stone/paver staircase back up to the side terrace. Your fence would go along the Level 2 wall and inside of the spa to enclose it as well, on it's way over towards the house extension area. There would be a gate there into the pool area (as well as on the back side where the yard steps are). I'd stop the fence short of the house extension area on the right so there is a bypass area to get out to the back yard on that side as well as the left side (though I can't see that side - it would be nice if the pool didn't extend all the way to the left side in your picture to allow for back yard access from both side). This also allow for a running route entirely around the pool for kids/dogs chasing each other.
 
There really isn't any better safety (aside from an autocover) than a separately fenced pool. I do agree that a fence around the pool would be great. I would go with aluminum and not wrought iron though. Iron will need recurring maintenance over time.

I might suggest in the bigger picture, looking at potentially removing the deck and instead, installing a small landing outside of the slider, then wide steps down to Level 2 which would now be a large space. That would create a more wide open and usable area on Level 2. Then you would build a stone/paver staircase back up to the side terrace. Your fence would go along the Level 2 wall and inside of the spa to enclose it as well, on it's way over towards the house extension area. There would be a gate there into the pool area (as well as on the back side where the yard steps are). I'd stop the fence short of the house extension area on the right so there is a bypass area to get out to the back yard on that side as well as the left side (though I can't see that side - it would be nice if the pool didn't extend all the way to the left side in your picture to allow for back yard access from both side). This also allow for a running route entirely around the pool for kids/dogs chasing each other.

Yes, yes, yes!!!! All of that! I went back and forth from the pic to this and it all makes sense! Pool area AND a yard play area! It will be pretty and safe. Put the pointed tops on the fence to keep little monkeys kids from climbing it! I would put the fence on all of level 3 (pool deck) so there will be seating and lounging by the pool.

Now I don't think I would allow the kids in the yard without an adult out there to be on the safe side for a LONG time.

Kim:kim:
 
One thing that hasn't been mentioned yet to add to the security chain, security cameras. For $130 you can buy a Blink outdoor camera that could supply a warning that a child has entered the yard from the back door or any other variety of motion detection. They're super easy to set up with your router and use an app to control and view from your phone. It's nice to be able to see anywhere inside or outside of your house from your phone no matter where you are. I have 3 of these cameras outside my house and use 3 Nest cameras inside.

https://blinkforhome.com/collections/outdoor-security-camera