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Halloween Costume Ideas: Simple Shark (with Dorsal Fin)

Okay, time for another costume idea.  Because, YES OH YES, there’s still plenty of time to make a few costumes before Halloween!


When I asked for simple Halloween Costume ideas a couple weeks ago, several of you mentioned wanting to make a shark costume.


Okay.  Done.  Sounded fun to me!  And good news……’s pretty simple.  And is just a variation of something you may have already seen floating around the web.


HOWEVER.  This guy has an intimidating fin, to help him swim through dark ocean waters.  (Okay, that shark face may not be intimidating…..but his fin sure is. Ha!)







Sharp teeth……check.  Beady eyes……check.  Pointy fin……check.  (Yep, still need to work on a scarier face…)





I’ve seen this shark sweatshirt idea floating around for a year or two and was just going to share the link to those of you who are interested, to Martha Stewart’s tutorial.  However, at the last minute, I decided to just make one real quick and add a quick dorsal fin on the back.  Any my little guy Connor LOVED IT!!!!


And don’t worry, there’s a piece of plastic canvas in there, helping it keep its shape…..but also a little padding to give it some shape.





The eyes and teeth are sewn right onto the hood of the sweatshirt……and let that little face poke right through.






And just think……those of you who live in super chilly climates, your little trick-or-treaters will be cozy warm in their costume!  (But just be sure to teach them a more ferocious stare!)





Oh yes!  There it is………WATCH OUT!!  This flesh-eating shark is ready to ATTACK!! :)



Ready to make your own Shark Costume??



Like I mentioned before, the concept of this costume has been around awhile. (And I think most give credit to Martha Stewart’s tutorial.  But maybe there are others??)  


So, if you’d rather skip the fin…….just stick with the eyes and teeth. 

However, a shark isn’t a shark, without his dorsal fin! :)




  • Grey Hooded Sweatshirt with matching Sweatpants
  • An extra pair of Sweatpants in the same color (get the largest size you can for this extra pair, to give yourself plenty of extra fabric)
  • A piece of Plastic Canvas (I think the sheets come in 12 x 18 inches)
  • White felt
  • Small circles of black felt
  • Batting



First of all, measure the opening of the hood, where your teeth will go.



Then, cut two strips of white felt that are 2 inches longer than you hood measurement…..and are about 2 – 2.5 inches wide.


Place the two strips together and sew a line of zig-zags along one of the long sides.  My zig-zags were about 1 inch tall and 1 1/2 inches wide……but this can vary.  (Just be sure you keep the tip of each tooth lined up along one side of the 2 strips and leave extra room along the other side for attaching to the hood.)



Then, cut out the extra felt, making sure to NOT clip through any of your seams.



Place your line of teeth along the inside edge of the hood, only allowing the triangles to show.  Pin in place (and cut off any extra from the ends).



Sew in place, with two parallel seams……making your teeth nice and secure to the hood.



Cut out two white ovals (1 3/4 x 2 1/4) and two smaller black circles (1 inch in diameter) from felt, to create your eyes.



Place the black circles on the white ones, and sew around the outer edge of each black circle.



Then, center each eye on either side of the center seam of the hood.  Sew around the white ovals, securing them to the hood.



Next, cut a fin shape from your canvas.  (The size of this can vary…….in fact, my husband thinks the one I made is a little large.  yeah, maybe…..but it all depends on preference.  As a guide, my fin is about 10 inches tall and about 9.5 inches wide at the base.)



Now, cut open your pant leg from the extra pair of sweatpants, right along one of the side seams.  I would have cut along the inner seam but I didn’t want to pick out that white stripe along the side of the pants, so I cut along the white strip.



Cutting the leg open creates a large flat piece of fabric to work with. 


Now, place your canvas fin on your fabric and cut around the fin, giving yourself a 1/2 inch on all sides (for a seam allowance)….except along the bottom, give yourself an inch or so of extra fabric.



Use the first fabric fin you cut out and place it face down on more of the fabric (so that the “right” sides if the fabric are together) and cut out a second fabric fin.  Keep the fins together, with “right” sides facing each other and sew around the two sides, using a 1/2 inch seam allowance.



Now, cut off the pointy tip of fabric and cut notches along the mountain curve (the right side below) and cut slits into the valley curve (the left side below).  Just be sure you DON’T cut through your seam.  (Not sure why you should clip the curves and corners??)



Turn the fin right side out and slide your canvas fin inside.



Then, place a little batting on both sides of the canvas to help plump out the fin.  (You don’t  need to stuff it full……just a bit to give it a little more dimension.)



Then, place the fin along the back of the sweatshirt, placed directly below the base of the hood and centered from each side.  Fold the raw edges of the fin under about an inch and then hand sew the fin to the back of the sweatshirt.  (Need help with hand stitching??)





And one last thing……this sweatshirt set came with white lines along the legs of the pants.  I just unpicked the lines of fabric so that they didn’t distract from the costume.  (And in case you’re curious, I bought this sweatsuit from Kohl’s.)



And that’s it.  A ferocious, yet friendly shark…….ready to swim the ocean waters!! :)



Have fun with it!






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  1. Pingback: 16 Fun & Creative DIY Halloween Costumes for Kids (Last Minute Ideas) - Fun for Little Ones
  2. Ln Bidouilles says:

    Thank you very much for this toturial ! Last thursday my son tell me he wants a shark suite for school carnival (on friday!!) And your tutorial saved my life, I could make his disguise in the evening ! He is very happy !! My creation on my blog (in french)

    1. Ashley says:

      I just looked at it….turned out adorable! I’m glad it worked out for you! Thanks for sharing! -Ashley

  3. Amy says:

    Thank you so much for such a great tutorial!!! My one question is how do you wash this?? Just by hand?

  4. Michelle says:

    Thanks for the tutorial! I just finished making a shark hoodie for my son to wear this Halloween. I added white felt on the front of the hoodie for the shark’s belly. It came out great! I’m so glad I found your post! Thanks again!! :)

  5. erin says:

    i found great hooded grey sweatshirt and sweatpants at the gap. they have 30% off now online too :>

  6. Jill says:

    Fantastic costume, so simple but really effective and I think my son will think it’s pretty cool too!

  7. Anonymous says:

    Thanks so much! My son told me today that he got a second role in the play he is in tomorrow and needs a fish costume! This is perfect!

  8. Sarah says:

    As always- ADORABLE!!!

  9. Erin says:

    So cute! I love that you have been doing boy costumes! We already have a plan for this year, but I have to pin this for future use! Thanks for the idea and tutorial!

  10. Ellie says:

    Super cute! One thing I have done on costumes before is to use a shiny black button (the kind with a shank in back) instead of a black felt circle for the eyes and it makes them look like giant googly eyes.

    One question: Does your sewing machine zig-zag that big or did you do that by stopping and turning the fabric every inch? I’m assuming you did it manually, but I wanted to verify.

  11. Tara says:

    I made this for my oldest last year, along with an orca (killer) whale for his youngest brother. I made my daughter who was still crawling into an octopus, and made sweatsuit sea turtle and crab outfits for my husband and I. They all turned out so cute, and were incredibly easy! The best part is that my kids still love them this year and want to use them again! How easy is that?!

  12. Doreen says:

    I liked the size of the fin. I think it looks better in costumes if features such as a dorsal fin are slightly exaggerated. Draws attention to it. Great costume. I can see my grandson wearing this all the time!

  13. cucicucicoo says:

    I love simple costumes like this! It’s so cute– I mean, so fierce! ;) Lisa

  14. Stephanie says:

    I love this! Sharks are my absolute favorite! I think I am going to have to make one for myself…HA! :)

  15. Jeanette H Kirkham says:

    Great thoughts!! I need to make a my little pony costume, thinking of a similar idea, using a sweater and adding yarn in the seam for the mane and tail. I need to make wings this year, the plastic canvas sounds like a great way to go to help them stand up!

  16. Kiran says:

    So cute!

  17. Nicole says:

    I was going to do this for my 3 year old but wasn’t able to find a gray hoodie anywhere. So cute!

  18. Sharon says:

    Super cute! Looks really easy too. Do you think you can do one up for adults based on the chipmunks, Chip and Dale?

  19. Emily says:

    So cute! I could easily do this!

  20. Shawna says:

    This is just toooooo cute! And a great tutorial!!! May have to make one for my grandson.

  21. Séco says:

    Love, love, love the idea. I might just make a quick shark costume for my toddler!

  22. Kelley says:

    Thank you for this! It gives me a great idea for my daughter’s Twilight Sparkle costume. We’re also in CO so it needs to be warm. :)

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Hi, I'm Ashley

Hi, I’m Ashley—the DIY-enthusiast behind this crazy blog!

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