We were having a BBQ party for the entire family. My cousin was invited and brought her five-year-old who also I guess is my cousin or related to me somehow. How she's related doesn't really matter to this story.
Anyways, they forgot we had a pool and that everyone would be swimming. The five-year-old wanted to swim so badly but nobody had any suit that would fit her as the other kids were much older and bigger than her.
So, instead of allowing her to go in with undershirt and panties my cousin said it wouldn't hurt anything to let her go in nude as she's only little and it's not sexual. As long as we made sure she had enough sunscreen it would be okay.
Anyways, when it was time to go in for food this little one wanted to swim longer and not get out of the pool. I was the one responsible for making sure she stayed in the shallow end and didn't drown.
That's when I noticed she had stopped swimming and had positioned her crotch against the jets and spent several minutes there with her head thrown back enjoying the sensations.
I didn't know what to tell her so I let her continue and pretend I didn't notice. I took her mum aside casually when she came back out and pointed out that her daughter was masturbating using the pool jets and said I dunno where she learned that as I don't want anyone thinking I taught her.
My adult cousin said that's it's cool and that she told her daughter about the jets and to try it before going in when nobody was looking. She pointed out to me that my little cousin loves playing with herself and as long as she was doing it alone and didn't get caught it was okay.
After she got out of the pool I was responsible for helping her change and noticed that she didn't want to get dressed right away. So, I left her alone in the shed and came back a few minutes later to find her vigourously fingering herself.
She told me not to tell on her. I told her it was okay, hugged her and that was the end of it. These days she's 2 years older and every time I go over to her place or go into her room to get her for dinner or bath time she winks at me as I know what she was doing prior.