Punarjani Guha is a natural tunnel 150 meters long in a rocky cliff in Thrissur district of Kerala state, south India. Punarjani Guha is situated 2 kilometres from the Thiruvilwamala Temple where the chief presiding deity is Sri Rama. The idol is believed to be ‘swayamboo’ i.e. born on its own. It is believed that performing ‘noozhal’ or crawling through the tunnel from one end to the other will wash away all of one’s sins and thus allow one to attain freedom from rebirth or moksha. Only men are allowed to do the ‘noozhal’; women can only visit the cave. The legend is that sage Parasurama once observed this ritual 101 times in a row to atone for the sin of annihilating the kshatriyas.

This ritual is practised only one day in a year on Guruvayur Ekadasi day, in the Malayalam month of vrichikam. The “noozhal” is a challenging task and not all can perform this ritual. Most people need about half an hour to finish the ritual. The movement through the cave demands all kinds of bodily postures like standing, sitting, creeping, crawling etc. yet every year thousands of men flock to this place on Ekadasi day to avail themselves of a chance to escape the cycle of rebirth.

Source:

http://en.wikipedia.org/wiki/Punarjani_Guha

http://www.deccanchronicle.com/141203/nation-current-affairs/article/hundreds-crawl-shake-sins  http://unnirajeevks.blogspot.in/2010_11_01_archive.html