A dramatic and atmospheric square audiobook cover illustration, 1024x1024. The scene depicts a colossal, ancient, vaguely Norse-inspired stone structure partially submerged in a turbulent, dark blue ocean. Glistening, faint golden light emanates from within the submerged ruins, hinting at hidden technology or power. Above, the stormy sky is a deep, moody grey with streaks of ominous purple and a single, piercing beam of moonlight breaking through. Jagged, icy-looking rock formations surround the area. The overall mood is one of mystery, danger, and grand ancient secrets. The visual style should be realistic with a touch of fantastical grandeur, evoking a sense of epic adventure and underwater exploration. No text, no letters, no words, no title, no author name.