The orchestral version by Leopold Stokowski
The electronic (Moog) synthesizer version by Tomita
Taken from the page for the orchestral version, The Engulfed Cathedral "evokes an ancient legend in which the submerged Cathedral of Ys rises slowly out of the sea, its bells ringing and priests chanting, and then sinks slowly back again into the watery depths."
For supreme weirdness, click all three and play them simultaneously. I suppose that would be your very own re-mix. ;0)