This coloring page depicts a large submarine at the center of the page with a variety of fish surrounding it. The submarine is a dark gray hue, while the fish are vibrant with color and contrast - blues, greens, yellows, and oranges hues popping out from the page. To bring out the vibrancy of the page, I would add darker shadows to the submarine and fish as well as some lighter highlights on the submarine's sharp edges and fins. The fish should be shaded to bring out the different colors, and I might apply some creative touches such as adding orange eyes to the fish or bright yellow stripes across them. To finish the picture, I would draw a few bubbles that have escaped from the submarine, adding to the overall underwater effect.