Draw underwater backgrounds that add depth and substance to a maritime scene. To design an underwater background you need plenty of examples to work from, such as photographs from snorkelling or books of marine life. The underwater background should reflect the appropriate environment for the subject of your drawing. For example, if drawing a clown fish, an underwater background should include a sea anemone since clown fish share a symbiotic relationship with sea anemones. If the subject is more inanimate, such as a sunken ship, images of sunken ships will provide examples of dark and light areas of the background for proper shading.
Select a background that matches your subject. If you have multiple subjects in your drawing, you should choose a background scene that reflects an area underwater where all of the subjects might coexist.
Look at your blank drawing paper and very lightly sketch an outline for any underwater structures or surfaces. This could be rocks or coral without a visible ocean floor, or it could be an ocean floor with minimal large structures. The subjects of the drawing will determine which is more appropriate.
Establish your light source and add details to the surface or structures outlined in step two but maintain light pencil strokes. Details will provide the basic images of the structures in the background and guide your shading or colouring later.
Draw your subjects over the background in the desired positions. Begin with light sketching then add details until the subjects' forms are nearly complete. If desired, add underwater plant life to interact with the subjects of your drawing. Unlike surface plant life, underwater plant life has a fluid and flowing appearance in the water environment and some of your subjects may be swimming through or hiding in the plant life.
Begin shading shadowed areas of the underwater background. Take into account the light source established in step three and the relative locations of the drawing subjects. As you shade the darkest areas, blend the pencil with a blending tool and layer the charcoal or graphite to produce a deep, textured, shading effect. If shading becomes too dark, use the kneaded eraser to press on and lift off graphite or charcoal.
Add colour, if desired. Colour may be added with coloured pencils or water colour paints for different effects. Use darker blues and greens in a blended, layered technique making the colour darker in the deeper water near the bottom of your picture and lighter as the drawing nears the water surface.
Shade the underwater background to be darkest at the bottom of your drawing since lighting becomes scarce when you move further from the surface. If using only pencil, blend the graphite or charcoal with a blending tool to reduce the appearance of any strokes or pencil marks which can take away from the underwater fluidity.
To employ this blended layered technique, apply coloured pencil and blend with a blending tool; use a different blending tool than the one for standard pencil to avoid making the colour all grey. If painting, thin the paints with water for lighter shades. Water colour pencils are a nice alternative that provide increased application control due to the pencil format.