Overall, very nice work and very nice environment. I've always loved aquatic environment and this scavenging submarine is one of a kind. I decided to go further into borrowing more from the Lobster design by reinforcing all of the aspect of the submarine design. The more you'll practice, the more you will get familiar with all of the shapes I used in here. For example you have a strong sense of rondness into the lobster shell and so I reused it to reinforce the sense of design. It's mainly get accustomed to form manipulation (especially cylinders and spheres in this specific case) I also figured the composition and the perspective could be reinforce. Here I used a trick I'm working with in 2D animation Background. When you draw, you can seperate you're all background between 3 main categories: Overlay (or OL) : Everything that is in front of your subject in the image (this case the rocks) Middle ground or Underlay (UL): Your main subject (most of the time) Background: Everything that is behind the subject. This is a short explanation, I invite you to look further into "animation layout" mecanic for more. The way I seperated this picture helped creating depth without adding perspective grid, though your submarine and fish still need clarity and perspective. I also added some plant and a school of fish to creat more variaty as well reinforce the eye track of your illustration. I hope this feedback will help you. Don't hesitate to reach if you have more questions. Best of luck! | Artwod Feedback