Start by sketching your blue whale onto canvas using a light pencil to help plan the composition of your painting. Next, use a thin brush to start painting in the basic colors of the whale. Start with a light blue for the body and a darker blue for the shadowed areas.
As you paint, add in more detail to the whale. Use white paint to add highlights and texture to the blue whale's body. Make the whale's belly a light blue and its back a darker blue. Use light and dark blues to create a sense of depth in your painting.
Finish up by adding in the final details, such as the whale's eye and mouth. Use a dark blue or black paint to create the pupil of the eye and paint the mouth in a light pink color.
Now step back and admire your work! You've successfully painted a blue whale in oil paint.