Ch. 3, Page 26

Curiosity overcame the adventurers. As Serten continued to enthusiastically wave them out of the mural room, they exited into the tunnel and formed back up into double ranks.

It became colder and colder as they came to the other end of the tunnel, until they could see their frosty breaths before them. They had been prepared for some explanation to the cold, but were still awestruck when they saw the cavern that awaited them.