How to Make a Dolphin Costume

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This dolphin costume is absolutely, adorably fin-tastic! And that's no joke—we're just squidding; it's a little bit punny. Whether the porpoise behind this dress-up DIY is to win best costume at your BFF's Halloween party or your kiddo is totally into water-dwelling mammals, we don't sea a reason to spend, spend, spend on an ocean-worthy outfit.


Don't stress if your Halloween costume creation mastery level is at "cut two circles in a sheet to make a super-not-scary ghost." That's why we have your back, tail and dorsal fin covered with this easy and—dare we say—artsy how-to.

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Video of the Day

With a few materials and some creative costume ideas, you've got this dolphin dressing thing down! Come on, crafting an adult or kids' costume shouldn't make you flipper out.

Things You'll Need

  • Cardboard

  • Clear-drying craft glue or hot glue

  • Scissors

  • Silver or gray craft paint

  • Paintbrush

  • Pencil

  • Permanent marker

  • Silver or gray ribbon

  • Large googly eyes

Flatten the cardboard boxes

You're all about dolphin-safe tuna, and you would never toss those plastic drink rings into the trash without cutting them into pieces first. Reuse, recycle, and do your bit to save the planet—as you create a dolphin costume!


Scavenge oversized boxes from your basement, garage or a friend's house to use for DIY Halloween costumes. Open the boxes at the ends and remove any leftover tape to make two separate flat surfaces.


Boxes not big enough? No worries here. Tape together a few smaller flattened boxes to make one bigger sheet of board.

Draw a dolphin outline

Use a photo or other pic to recreate a dolphin in profile on one of the flattened cardboard pieces. Don't forget the dorsal fin on top, the flipper on the bottom and the notched tail at the end. The bigger the board, the larger the dolphin. The larger the dolphin, the longer the Halloween costume.


While you're at it, go ahead and use the same technique to DIY a fish costume, whale costume, shark costume or starfish costume, or go all-out Disney and craft your own mermaid costumes based on the iconic Little Mermaid character.

Cut the cardboard

Cut out the dolphin profile from its beak-like snout to its tail flukes.


Trace the dolphin

Create an identically sized dolphin on the other piece of flattened cardboard. Place the first dolphin onto the flat board to use as a template. Trace the outline and cut out your new drawing.



Paint the dolphins

Each dolphin cutout goes on one side of the sea animal costume. This means you won't need to paint both surfaces of each drawing. Sandwich the two pieces together. Mark a small pencil "X" on the side of each dolphin that faces out.


Place the dolphins on a flat, covered work surface with each "X" facing you. Paint the cardboard a silvery gray hue.


DIY costume-making is messy! Skip the salty sea-colored floor and cover your workspace with newspapers, flat garbage bags or more cardboard.

Add eyes and other accents

Glue one large googly eye onto each dolphin profile. Use a permanent marker to draw a line on the beak for the dolphin's mouth and a blow hole at the top!


Thread straps into dolphin costume

Make two one-inch slits on each dolphin cutout. Poke the end of your scissors through cardboard on either side of the dorsal fin. Cut the board to create slits.

Push a thick silver or gray ribbon through the first front slit. Tie the ribbon around the cardboard tightly. Attach the other end of the ribbon to the second dolphin cutout. Repeat for the rear slits (behind the dorsal fin). The length of the ribbon depends on the person's size. Obviously, under-the-sea costumes for kiddos will have shorter ribbon lengths than homemade costumes for grown-ups.

Glue the two beaks together

Put the dolphin on and pull the cardboard beaks together. Glue the insides of the beaks. Hold the dolphin's nose/mouth together for a few minutes. Wait to wear the costume until the beak is fully dry.

If regular glue won't stay put, swap it out for hot glue. This will keep your sea creature costume in place now and for every birthday party or Halloween party to come!


It shouldn't surprise you that hot glue is...well, hot! Avoid skin-to-glue contact if you're going the hot route. If the glue won't hold the heavy board or you're not into hot glue, staple the two sides together.

Glue the tail together

Look up! Those steps that just helped you to glue the beak are now up for reuse. Turn the costume around, add a few squeezes of glue and mash those flukes together.

That's it! No sewing, Pinterestingly fancy DIY dolphin costume crafting processes or Ph.D.-level structural engineering needed. Wait for the glue and put on an all-gray bodysuit, T-shirt or hoodie before you step into your Halloween costume. We bet you're dolphinitely the best-dressed ocean-going mammal of the cosplay "sea"-son.