I think Disney's The Little Mermaid was my Jacques Cousteau. I was six years old when the movie came out; I don't recall having any particular feelings about the ocean before then, but I've felt drawn to it ever since.
I didn't get around to scuba diving until my late twenties, when I did a discover dive with my then- boyfriend. I loved it--I don't remember seeing much, but breathing underwater was the most profound spiritual experience of my life. I didn't know much about diving except that I couldn't afford it back then. It took about a decade more for that to change, and then I was delayed a few years further when I found out my new husband wasn't medically fit to dive. Eventually I said screw it and got certified without him.
Mermaid stuff has weirdly become fashionable among a subset of my age group. Rainbow hair colors, known as "mermaid hair," is becoming increasingly common; you can buy a mermaid tail costume to swim in (and people get together to do this), and a couple of women I knew in high school have side hustles dressing up as mermaids for circuses or renaissance fairs (I don't get that one either). I played with some temporary blue-green and purple hair dye before my last trip, and it was fun. But for me, scuba diving really feels like living out my childhood fantasy. And I may or may not have a few photos of me collecting plastic dinglehoppers underwater. Still looking for a snarfblatt.