Research the blue whale's habitat and the animal's physical characteristics. Blue whales in the northern hemisphere are smaller than those in the southern hemisphere.
Cover the inside of your box with blue construction paper or blue tempera paint. The box should be the size of a large shoe box or bigger, if possible. Consider adding blue plastic wrap to simulate ripples in the water.
Create seaweed and other oceanic plant life using construction paper or plastic grass from an aquarium store. If possible, walk along a beach to collect sand and sea shells. Gluing these items to the bottom of your box will add depth and detail.
Draw or print out a picture of a blue whale. Blue whales are actually a marbled gray color on top and usually a lighter gray, or even white, underneath. It's also common to find barnacles growing on the undersides of whales.
Hang the blue whale from the top of the box using glue and string. Be sure that the whale can hang freely so it looks like it's swimming.