The word 'canyon' describes a narrow valley with very steep or vertical sides carved by a river. At Matka, the cliffs rise up to 1,000 metres above the river in some places. The rock is mostly limestone, which is a soft rock that water can slowly dissolve and carve into dramatic shapes - caves, arches, and tunnels.
Inside the caves of Matka there are wonderful formations called stalactites (hanging from the ceiling) and stalagmites (growing up from the floor). These form over thousands of years as drips of water leave behind tiny amounts of mineral. One cave, called Vrelo, has an underground lake inside it that is thought to be extremely deep - divers have gone down more than 200 metres and still not found the bottom!
Visitors to Matka can take a small boat across the man-made lake, hike along the canyon walls, and explore some of the caves with a guide. The water in the lake is a stunning emerald-green colour because of minerals dissolved in it from the limestone. Butterflies and dragonflies dart across the surface, and if you are lucky you might spot an eagle circling high above the cliffs.