A whale costume can be an interesting and easy costume choice for a Halloween party, costume party or simply an aquatic themed day or event at school. A whale costume can be made for a baby, child, teenager or adult out of many items and supplies you already have in your own home. Choose colours for the whale costume that will not be easily confused with other marine life, such as dolphins or sharks. For example, crafting a killer whale, which has signature colours of black and white, will make an easily recognisable whale costume.
Purchase a black hooded sweatshirt several sizes too large. The bottom hem should hang below your waist and above your knees.
Cut an oversized white T-shirt in half, separating the front of the shirt from the back. Sew the T-shirt front to the front of the sweatshirt, lining up the shoulders and neckline with that of the sweatshirt.
Cut two white circles and enough triangles to line the entire front of the hood of the sweatshirt. Sew the circles on either side of the top of the hood and the triangles so they protrude out from the front of the hood as teeth.
Cut a dorsal fin shape, which is a triangular, horn shape and a whale fin, similar to the shape of a "Y," out of black pillow cases, making sure to cut through both the front and the back. Sew together all seams except the bottom of the "Y" fin and the bottom of the triangular dorsal fin, forming pouches.
Stuff both the dorsal fin and the tail with batting until they are full. Sew the dorsal fin to the middle, back of the sweatshirt and the tail to the bottom, back of the sweatshirt.
Wear black tights or leggings and black or black and white sneakers to complete the whale costume ensemble.