I remember this show from when I was younger. It was about a family who took their two sons to live in this underwater little place and there were lots of other people there too and one day the one boy discovers this girl in the ocean who can't speak but swims amazingly.
I dont' remember any story lines really at all but i'm sure the episodes are on youtube if you want to see them.
The people talked with accents and the ocean girl didn't swim the way we did and sort of just almost wiggled through the water without moving her arms or feet.
I remember the opening title song vividly and for some reason I have always remembered this show. It will stick with me forever.
Plus at the time I had a huge crush on the Ocean Girl herself, I mean who wouldn't?