Ocean Girl was a live-action Australian science fiction children's show that syndicated in the US on The Disney Channel during the 90s (but only the first three seasons, I wasn't even aware there was a fourth season until much later). The entire premise centers on two brothers and their discovery of a mysterious girl, Neri, who lives alone on an island and who can swim unprotected in the ocean for long periods of time. The series focuses primarily of their friendship and bond with Neri while keeping her secret from others who might want to exploit her, but also uncovering the truth of her origins along with helping her protect the ocean and nature in general. This is a series that I grew up on, this is literally a huge formative piece of my childhood that has shaped me into who I am today.
I really wish there were more shows like this out now, because even for a kids show it was quite intriguing, filled with mysteries and suspense, but also a kind of whimsical wonderment. It also got me curious about marine biology and environmental activism as a kid. And also I wanted to become Neri because, come on, who didn't want to live on an island and swim with a humpback whale? I know the creator of Ocean Girl also went on to create H20: Just Add Water years later, a show that while different shares similar themes and concepts, and I've read there's been talk about possibly reviving both shows, but I haven't heard much outside of that.
If you haven't seen Ocean Girl, I highly recommend doing so. Every episode is only half an hour, so it'll be a nice thing to binge-watch. I honestly like that they uploaded it for those unable to have accessibility to the DVDs. It really is a fantastic series that I feel more people need to know about.