Halloween is such a fun chance to dive into the mysterious & splashy undersea world, and we love celebrating with under-the-sea costumes! (Of course, these don’t have to be just for Halloween – they’re great for birthday parties, costume parties, a trip to the aquarium, or dress up play.)
So, we’ve decided to round up a bunch of our favorites (many of them are even DIY) so that they’re all in one happy place. Mermaids, scuba divers, and all sorts of sea animals! Sooo exciting!
For more Halloween and ocean fun, we’ve got just the thing for you: our children’s book (ages 4-8) called Shalloween features a flashlight fish named Ray who glows when he gets scared. The fun tale takes you under the surface with Ray on his very first Halloween party as he encounters new friends the ghost crab, vampire squid, the goblin shark, and many more! Our hand-drawn and hand-painted illustrations are colorful, fun, and lively — and feature real ocean animals to enjoy in the comfort of your home. Check out Shalloween on Amazon here!
And for ocean fun all year long, enjoy the rest of our children’s books on Amazon too!
Let’s dive into our costume roundup! You’ll find lots of inspiration here that’s great for kids and adults alike. You can click on the underlined text or images to go to the website that each is from.
Bonus DIY Fish Mask
Since the making of this post, we’ve created a DIY Fish Mask and included it here to add to the fun! We used a disposable mask, paper craft mask, shiny wrapping paper, and cupcake liners (click the image below or the underlined text to visit the page):
1. DIY Scuba Diver Halloween Costume
Such an adorable idea! Soda bottles are used for air tanks (secured by electrical tape), along with simple black pants and shirt, and a mask and snorkel. There’s even a “weight” belt made out of electrical tape and hair curlers!
2. DIY Simple Shark Costume
What a great idea to use a sweatshirt hoodie for this costume!
3. DIY Octopus Costume
Giggles Galore gives DIY instructions using tights, a hat, long sleeve shirt, a belt, white & black felt, and cotton batting.
4. DIY Jellyfish Costume (2 options)
What a jelly-tastic DIY, for any age! This one is electric with lights:
And here’s one from Alpha Mom that uses an umbrella:
5. DIY Stingray Costume
Here’s one that’s great for last minute scrambling! We love the details of the mouth and gills on the underside to make it more real.
6. DIY Starfish Costume
This simple cardboard cutout uses a pool noodle for the tube feet!
7. DIY Lobster Costume (2 options for DIY)
This Martha Stewart tutorial is complete with a claw template and instructions that are adaptable for any age. Don’t you love the ping pong balls as eyes?
And this baby lobster costume isn’t DIY, but it’s just so clawfully cute:
Couldn’t resist including this one, either (has the option to buy the pattern for about $5):
8. DIY Seashell Costume
Another one from Alpha Mom, what a sweet costume that has a giant pearl to top it off!
9. DIY Dolphin Costume
LOVE this! MindOverMessy even included printable patterns.
10. DIY Mermaid Costume (3 options!) + Tiara (2 options!)
Being a mermaid is a dream for many little girls (myself included!) and is a timeless costume that all ages will adore. I just love mermaid costumes, so I decided to give you several options. To top off whichever one you choose, there are two DIY tiara options that are fit for a mer-princess!
Here’s a quick-sew version with stunning sheer organza scales, complete with a video tutorial:
Here’s a no-sew option for those of us that are a little more challenged in that area:
And here’s one with coffee filters for the scales that the kids can color themselves!
To top the mermaid costume off, here is a DIY royal addition of a sea-jeweled tiara. Try and find faux starfish and use shells that you’ve collected instead of buying them. (By doing this, you’re not supporting harmful harvesting practices that are hurting marine species.) Click the picture below or here for the video tutorial.
Here’s one more tiara option, this one uses a headband:
Ok, I couldn’t resist adding one more: a mermaid baby costume! I haven’t gotten into crochet yet, but this looks like it might be a simple design to replicate for those of you who know crochet. Is this not the most adorable mermaid costume you’ve ever seen?
Just seeing all of these costumes makes us want to dress up too — what better excuse is there to dress up as a mermaid, scuba diver, or favorite sea creature!?
To go along with your ocean-themed costume, make Halloween even more fun for the whole family with with our undersea Halloween children’s book! Click here to find Shalloween on Amazon.
Have a fin-tastic Halloween!
Your costumes are adorable!!!!
Thank you! We had a blast gathering the round up from so many creative bloggers! 🙂
They were awesome. Did you check out ‘Garden’ and ‘Summer’ and ‘Home Decor’ categories? You will see I love everything beach!
Love it! 😊
Thank you! I love makeovers, and re purposing!
Thank you for including my DIY Dolphin costume in your ocean round up. I love the name of your page and the idea! I was thinking of being a jelly fish this year and this round up gives me some easy ideas. Btw- I also have a Sea Turtle costume made from felt and a couch pillow, of all things – http://www.mindovermessy.com/diy-sea-turtle-costume/. Nicole @mindovermessy
Nicole – the sea turtle costume is adorable! So glad you liked the round up, and it was our pleasure to include your fantastic dolphin costume. We’re glad our post was helpful for your jellyfish costume endeavor and thanks so much for your note!
Thanks so much for including our mermaid tail and tiara in your round-up! Loving all the ocean-themed ideas. Too cute!
Thank you, Meghan! We loved including your mermaid tail and tiara, so fun. Glad you liked the ocean-themed ideas!