18. Samariá Gorge, Greece

This rocky canyon is ensconced near the quaint village of Samariá in western Crete. See it all from the popular 16 kilometer (10-mile) hiking trail. You’ll climb to see incredible views of the White Mountains after wading through crystal-clear water. So pack your hiking boots to deal with the rocks and other challenges. Hiking here can be difficult during the summer.

19. Subway Canyon, USA

Subway Canyon is a short yet noteworthy portion of the memorable Left Fork of North Creek, in Utah. The canyon was created by a lava flow which actually pushed through the rock. Hike the seven-plus mile trail from Wildcat Trailhead to Subway. It involves hiking, wading, and swimming! It’s a popular place so be sure to get your permit in advance.