I'm tinkering around with an idea based on a mermaid civilization unbeknownst to humanity. The problem is, I'd rather write this with a better knowledge of what's scientifically possible, as opposed to pure fantasy.
My main question is how advanced could an underwater society be? Technology as we know it couldn't be practically implemented, so what sort of concepts could I play with?
I'm thinking I may just have to resort to them being more of native tribes. It's the only way I can think of them living without possible detection from humans.