To create a better sense of movement, we will make a scrolling background. This requires two identical background images that will be sliding horizontally across the stage. As we want to move these backgrounds around, we won't be creating them as actual background images but as sprites instead. Sprites can be moved with scripts, while background images cannot be moved.
Let's create the image first. What we need is something that looks like an underwater view. So the main color should be blue, with a lighter shade of blue to the top resembling sunlight shining on the water surface. I also added a light brown strip to the bottom to resemble sand.
To create this image, I used Photoshop. However, if you don't have an external image editor, you can also create a similar image in Scratch. The most important thing to take note of is to make the image as big as the stage, that is, 480 pixels wide and 360 pixels high.
