Rock Lake diving

[mud_diver]

There are several good books on the subject. I will get you the titles and author tomorrow if intersted. (I have to find them at home). One in particular describes how they were discovered, the investigation into their Indian origins and the diving conditions. The author write about how some of the pyramids are completely covered  in silt. They show up on sonar due to the sonar penetrating the silt layer, but when the divers go to find them, they can not. Quite interesting reading, although I found some of the book difficult to follow due to my lack of knowledge of Indian history and culture.
For more information, check out: if you have not already.