Photoreal Demon in an Underwater Cave

A hyper-realistic, photorealistic depiction of a demon underwater in a dark sea cave. The demon features sinewy, scaled skin, ember-red eyes, and twisted horns encrusted with barnacles. Bioluminescent markings glow along its shoulders and spine. It hovers among jagged stalactites and submerged rocks while blue-green light filters through cracks, creating shimmering caustics on its wet skin and glistening teeth. Tangled hair or fins trail behind as currents swirl fine silt and bubbles rise. Surrounding the cave walls are ancient carved runes, illuminated by passing bioluminescent creatures. The atmosphere is eerie and majestic, with ultra-detailed textures, realistic water distortion, and a cold, oppressive depth.