In an empty boat berth at the Discovery Harbour Marina, hundreds of young herring were dancing. There's no other word for it; they swirled in loops and figure eights, twisted down into dark water, then leapt to break the surface, creating rows of winking lights. They split into groups, which met and mingled in complex patterns, then pivoted to promenade stage right, in unison. All that was missing was the music.
All together now
(The water reflected the clear blue of the sky, and a few clouds; the herring were silvery grey. I saturated the colour and increased the contrast to define the herring.)