Algol - Follow the Cepheid Light (2008)

As far as ambient, dark or otherwise, this is pretty much as good as it gets (at least for me). It's an absolutely stunning example of space ambient on par with the work of such luminaries as Steve Roach and Robert Rich. The textures take you on a fascinating and beautiful trip through the imagination and metaphorically into the farthest reaches of the universe. It's certainly the best underground ambient album I've found yet, and one of my all-time favorite albums in the genre.
10/10