In the Varadaraja Temple across from our Kanchipuram house, there is a special area (seen above) where the deity is considered to be so powerful that it has to be kept under water in the temple seen on the left. The murti is taken out once every 40 years! And even then only for a week or so for a festival and then back into the water. Apparently there are only a very few people who have even seen it twice.
Aside from the obvious curiosity of the story, it also shows how old some of these traditions are and how carefully they are maintained over time.