I remember this vividly.
I was about 3. Was in my aunty's pool, she was having a party. My older sister took me around the pool and sat me on the edge of it. I looked at everyone else swimming in the pool having fun and thought hmm I can do that on my own too. So I slid into it, right to the bottom of the pool. I was there for a while. I remember seeing everyone's legs kicking around under the water. I felt very peaceful, wasn't struggling and made no attempt to get out of the water. I was eventually pulled out if the water by someone who saw me and luckily I was ok, I don't know exactly how long I was there but I didn't need any CPR, there was some coughing but nothing major.
I can't believe someone actually saw me under there with so many other kids in there. I was meant to stick around.
I've never ever forgotten it all and tbh put some if my anxiety (had it severe as a child) down to it.