Old and widespread European traditions ascribe magical and healing effects to passing through holes. In Sweden passing children through a hole in a tree was called Smöjning, and in the far north it survived until recent times. The older traditions suggest Smöjning for changelings, but in the twentieth century it was mainly done for respiratory conditions. This photograph is from the 1930s.
A famous Smöjtrad, or Smöjning tree.
Children could also be passed through holes in the ground, which in Sweden was called Jorddragning.
In the Celtic world the traditions mainly focus on stones, such as the famous Men-a-Tol of Cornwall. Here adults often crawled through the stone holes themselves, seeking either cures or forgiveness of sins. Of Men-a-Tol it was said that if you could crawl through without touching it, you would never get rheumatism.