I rewatched the Disney movie, Atlantis: The Lost Empire, for the first time in over 10 years and was quite surprised to learn that there was an actual language used by the Atlanteans.
After I finished the movie I decided to look it up and see what this "Atlantean language" really was. It turns out none other than Marc Okrand, the inventer of Klingon, created the language for Disney! What's even more amazing is that Atlantean is a full language not just a list of some words.
However, it turns out the copyright (you can apparently copyright a language) is under Disney, and they've decided to not let any of the details slip out to the general public. Some other speculate that originally they planned to continue to use the language as a way to engage the fandom, but after the movie flopped most it seems to have just been swept under the rug.
However, in an amazing Internet story, Atlantean seems to have transcended its own fiction and amateur linguists have actively worked at cracking the language with what little information is available, much like is done for real ancient languages.
Unfortunately, it seems most activity on Atlantean has died down, and most of the websites that once hosted useful information seem to be offline now. Fortunately though, the Atlantean Language Institute is still online, and although the site is messy, it has a lot of great information.
The site's creator, who goes by the name Keran Shadlag in Wiltem Adlantisag, has a contageous enthousiasm for the language that really lets you get a peak inside the head of someone passionate about historical linguistics.
The Atlantean language itself is rather interesting too. It was designed to be a kind of "root language" for all the languages on Earth. In the movie this is used as a kind of Deus Ex Linguae, so the Atlanteans can understand all languages on Earth.
While the concept is a bit much, the idea did lead to the creation of a rather interesting language.
When I stumble upon something like this I always wonder how far the language can actually be used, and have spent the last couple of days reading up on what little information their is in an effort to make myself competent enough to use the language. At the moment I've only been adapting the existing canon and formating in a way that makes it much easier to follow. Time permitted, I'd like to then take that and make viable lessons that I'd publish here or something.
To finish for now though, here's a fun video where Marc Okrand teaches some basic things in Atlantean: