Matka Canyon is a limestone gorge on the Treska river fifteen kilometres outside Skopje, in North Macedonia, flooded by a dam of 1938 into a lake of green water between cliffs, with medieval monasteries on the slopes above and one of the deepest underwater caves in Europe below the surface, and it is paddled by kayak, boated to a cave and climbed on grey limestone rising straight off the water. The dam was the first in the country, and its wall has spent a second life as flood insurance for the capital downstream; the lake it made fills the gorge for several kilometres, and from the jetty by the dam kayaks and pedal boats go out at water level, where the canyon closes around the boat, walls rising straight out of the green with bays the tour boats never turn into, and a ten-minute boat ride upstream ends at the mouth of Vrelo cave, where a lit walkway runs past stalactites to two quiet lakes and a shaft that divers have followed to more than 200 metres without finding the bottom. The gorge is the country's main climbing ground, with five sectors of limestone from bolted single pitches to trad lines of 150 metres.
The monasteries are the other layer. The little stone church of the Holy Mother of God at the canyon mouth has stood since the fourteenth century, its walls repainted in 1497 by a noblewoman named Milica, and a quieter path climbs beyond the busy lower canyon to St Nicholas Šiševski, a monastery perched high on the far slope with frescoes from the 1630s and an iconostasis of 1645, while St Andrew's stands by the water near the dam. The gorge sheltered species through the ice ages, and eighteen insects were described as new to science from this one canyon; the Ramonda nathaliae, a purple-flowered relict that spends the summer shrivelled to a dry husk, rehydrates and flowers on the shaded limestone from late April into May. Matka is a canyon a dam turned into a lake, and the monks and the divers share it.