Fjadrargljufur Canyon, Iceland

Fjadrargljufur Canyon is a 100 meter deep canyon with moss-coated walls. The canyon was carved by the Fjaora River over millions of years, likely at the end of the last ice age. The river's erosion created a deep channel in the palagonite bedrock, which is thought to be about two million years old. It's a fairly short hike up a steep and sometimes very narrow trail to this viewpoint, but worth the effort.