This is a delightful picture of a boy playing with a toy dolphin in a pool. He is wearing bright blue swim trunks and is holding the dolphin, making it move through the water. The dolphin is a beautiful sky blue with soft white accents. To make it stand out, you could use different shades of blue to color the dolphin, ranging from a light shade for the white accents to a deep shade for the main body. You could also add a hint of yellow and green for a subtle hint of brightness in the water and combine them to create a splendid underwater scene. Finish it off with a few scattered pink and purple hues for a bright and vibrant image!