This looks great, and the composition is nice. The only thing I can really critique is the sand. It looks like the sand you used is actual sand, which is out of scale at this size. It looks more like river stones than sand when compared to characters. You'd need something more powdery in its consistency to make 1/35 scale sand.
You could use something like Woodland Scenics Fine Buff or Talus, but I find that even those seem too big. I read somewhere that the sand they sell in pet-stores for reptiles is a very fine, powdery sand, and from what I can remember of viewing reptile enclosures at pet-stores, that's probably true. You could also check out the aisles at your local supermarket for powdery sand coloured substances. Spice aisle would be the best bet. And the cheapest option would be to take the current sand your using, in larger quantities, and sift it to get the really fine sand out of it. Once you have an option for fine sand though, mix in a bit of the current sand to approximate the random stones you find a on a beach, and your dio will look perfect!
Also, I know you're not done yet, but a friend of mine uses this pic as a reference for beach scenes. All sorts of lovely detail options with rocks and seaweed and varying types of rocks and sand. And if you're able to figure out how to make that wet-sand look where water has just retreated from the scene, WOW, that would make a dio pop!
