The most difficult canyons riddles

The Tara is a river in Montenegro and Bosnia and Herzegovina. It cuts the Tara River Canyon that is 78 kilometers long and has 1,300 meters at its deepest.

Zion National Park is an American national park located in southwestern Utah. A prominent feature of the 229-square-mile (590 km2) park is Zion Canyon, which is 15 miles (24 km) long and up to 2,640 ft (800 m) deep. The canyon walls are reddish and tan-colored Navajo Sandstone eroded by the North Fork of the Virgin River. Park includes mountains, canyons, buttes, mesas, monoliths, rivers, slot canyons, and natural arches.

Colorado River established its course through the canyon at least 17 million years ago. Since then, it exposed about two billion years of the Earth's geological history.