Hydrogen Sulfide River Silhouette Underwater Sardinia

Bright midmorning light penetrates the green water, fractured by rippling surface patterns that dance across the seafloor. A dense, dark river of hydrogen sulfide flows horizontally above a sprawling meadow of seagrass. The gas plume appears as a stark silhouette against the illuminated background, its edges softened by a haze of suspended plankton. Autumn leaves drift lazily within the current, caught in the slow motion of the underwater stream. The seagrass blades sway gently, their tips illuminated by the shifting light. Shadows stretch long across the sandy bottom, marking the depth of the cave system above. The gas layer creates a sharp boundary between the dark flow and the lighter water surrounding it.