Subterranean Glacier in a Photorealistic Underground City

A colossal glacier carving through the heart of a vast underground city cavern, photorealistic and ultra-detailed. The ice glows with cobalt and sapphire hues, revealing deep crevasses and trapped air bubbles. The cavern walls are a mix of rough basalt and carved arches, staircases, and crystalline ice columns forming a surreal plaza. Bioluminescent tubes line the ceilings and wall alcoves, casting cool blue light and warm amber pools on ice and wet stone. A translucent ice bridge spans a shallow river; distant figures in exploration suits move through frost-kissed streets, giving scale. Soft mist hangs in the air; volumetric light streams from skylights and vents high above. The scene blends natural ice textures with architectural city design for a cinematic, photorealistic 8k rendering.