Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app. Royal Arches, Yosemite. Kor-Ingalls Route, Castleton Tower. Durrance Route, Devil’s Tower. What do these super-classic moderates have in common? They each have a physically demanding chimney. This term refers to any fissure that your body fits inside, ranging from a squeeze chimney (one to two feet wide) to much wider, where you must stem the gap with a foot and hand on each side.