You woke up as if you have been napping for 8 hours straight, and discovered that you were breathing underwater when you found yourself staring at a bunch of seaweed. You could also see dark brown dirt that contained a starfish, and a bunch of sea sponges filled with shrimp that you thought wouldn't be living there.
You didn't know how you got their, but all of a sudden you take a look at yourself, and find a familiar looking tail below you, and see it curl up as you move from above the ground you were off of. You didn't think you were doing this, but below your hips you spotted a stitching pattern, where your waist was ending, and discover that your human legs have been replaced with a seahorses tail. You could also find a hole below your stomach you spotted some genitals that you think would pass you as a male half seahorse.