A colossal underwater metropolis built into a massive oceanic trench, towering crystalline biodomes housing underwater forests with bioluminescent coral structures and glowing jellyfish floating through glass corridors. Submersible vehicles with phosphorescent trails navigate between giant kelp towers reaching toward the surface light above. Deep navy and electric cyan palette with shafts of sunlight piercing the water from above. Epic wide shot with tiny diver silhouettes on observation platforms emphasizes the monumental scale beneath the waves, photorealistic, cinematic depth of field