If you’re using mesh distance fields, you could likely trace out further from the shoreline in increments and add the result as a “white” color to get those swirls/drawn-waves that trace the shoreline. I used a technique to get mesh distance field info further than the source by stacking trace distance calls in the material, the thread where I learned how to do it from @RyanB can be found here, perhaps you could modify it to fit the xy checks you’d need to do this.
Best of luck!