So I have an original species that I'm creating called the Larimar. I have a picture of them below, which I drew. I'm still working on the backstory for these folks, and I don't want to give away too much but heres a little info on them.
There are a number of underwater cities that have been there a very long time. Before the Larimar, although some do visit these ruins. There are great tunnels, made of a durable, phosphorescent material (which looks like crystal, but I'm playing with the idea of it being bone of a celestial creature). These tunnels are so strong, that they can withstand the pressure of deep sea.
The Larimar will live within these tunnels, as well as hunt from the few areas that allow them to meld into the deep sea waters (by magic of course). They are an amiable race, who interacts with land dwellers. Sometimes in these tunnels, sometimes on land.
The big question is this: I know of only a few species that can travel into the depths of the ocean, and then be able to come up, and survive at the waters edge, where us humans live. If my species was able to do this, what appearance would be more likely if they were once land dwellers? (humanoid)
I hope that is clear enough of an edit to reopen as I am very interested in hearing peoples answers.