To Dorgath and Nychus - This part of the cavern is natural, unlike the carved stairs and halls of the other side of the lake. The "beach" extends about 50 feet from water line to cave. I'd say you got about 10 feet from the cave when you first hear the noise. It's not a voice, but more like an animal's growl. To all other players - You pile into the boats. You all just fit, barely. You then begin to cross the lake.