This is a part of Iobaria that I have wanted to know about for quite some time.
However, I have noticed a slight error in the book. One page 26, once you have your PC's fighting the Frost Giant in the corridor heading into area C3. The title for this area is actually in the paragraph about the Development and how this Frost Giant calls for help. The title of this room is on the end of that paragraph. Not a big deal but in case others get confused by the description following this paragraph.