No, I believe there's no common lore about the people who live underwater from Indonesia. I think the artist do it solely on his imagination plus several inspirations like the Koinobori, if I'm not mistaken, is from Japan.
But we do have the most beautiful underwater garden here(such as Bunaken).
I also believed the work had come purely from the imagination of the artist, I was only wondering if there were some inspirational material present. I wasn't aware of, until your reply, the Koinbori or the Bunaken. For telling me of them, I thank you
Awww, the wonderful imagination and creativity of a child shown right in this picture This is really cool, it had a great amount of detail. Good job on the shading, shading and lighting are very important when making an underwater look. I love the sand tower and how the kids made their own little world. Awesome job