Create an underwater scene where a group of fierce mermaids swims swiftly through the ocean, heading towards pirate ships on the surface. Show the mermaids adorned in elegant yet formidable armor made of shells, coral, and glistening scales, designed for battle. Each mermaid holds a weapon, such as a trident or sword, that gleams with an otherworldly light. Their hair flows behind them as they move with powerful, fluid motion, eyes set with determination. Capture the play of light filtering through the water, illuminating the scene and the shadows of pirate ships above. The atmosphere should be intense, evoking a sense of imminent battle as the mermaids prepare to engage.