Here’s an image that was created in Adobe Illustrator. The whale could’ve been drawn with the pen tool or had been an original image that was recreated using the trace tool. The same applies to the birds. However, the artist only needed to create one bird and then the bird could be copied and pasted and mirror flipped to create multiple identical birds. I imagine the waves were created that way as well. This image just involves heavy use of the pen tool and active paint bucket. I think this is an awesome image, personally.