Photorealistic cross section view of a massive deep African lake, top half shows beautiful calm lake surface with green mountains and dark stormy sky, bottom half shows deep dark underwater view with trapped glowing green and yellow gas bubbles accumulated at the bottom, gas looks toxic and dangerous, deep dark water separating surface from deadly gas below, dramatic lighting contrast between peaceful surface above and deadly danger below, cinematic color grading, deep teal and dark green color palette, ominous and mysterious atmosphere, ultra sharp, 8K resolution, photorealistic, scientific documentary style, no text, no borders, no labels