Matka, meaning womb, canyon is located 15 km from Skopje. We explored this canyon by boat and foot for a few hours one morning of our Macedonia excursion. There is an underground spring called Koritište, offering water supply of 2 meters per second and it's considered a future resource of water for Skopje. Our guide didn't say too much–-he mentioned that there are a bunch of endemic butterflies fluttering through the canyon but that's all I remember--but the canyon is stunning so I have a bunch of photos to share.
Vrelo Cave, one of ten along the canyon. This cave (and I think the canyon as well) was listed as one of the top natural sites in the world in the New 7 Wonders of Nature project. To put it in perspective the list has something like 70 wonders so it's not only one of 7. Pictures don't turn out well in caves but I promise it was really neat inside.