My first inclination was to assume Atlantis was done with CGI. But then I came across the year it was made and realized that the technology didn't yet exist in 1991. We were still at the level of "The Mind's Eye" then, an experimental cartoonish attempt at computer animation in a video set to techno and released at Radio Shack if you remember. No, this is real footage, and it is perfect and amazing. It certainly isn't something I could sit through at a theater, but is suitable for meditation and falling asleep. There is no dialog, putting the movie in the same genre as "Samsara" and "Baraka", but a completely underwater experience. The symphonic and ambient music is very easy to listen to, but if it isn't your thing you can always just turn the volume off and play your own music. It's an incredible accomplishment in cinematography and something you can keep around to play at bed time.