20 Under the Sea Costume Ideas To Make a Splash This Halloween

For maybe a few dollars at the dollar store, kids can have a DIY jellyfish costume that really lights up.

It’s simple to make and guaranteed to be a one-of-a-kind Halloween outfit.

Here are very thorough instructions to make an adorable mermaid tail costume for kids.

There’s even a no-sew option for parents who are needle and thread challenged.

Little fans of the classic children’s book will be sure to love this DIY costume.

The Rainbow fish really comes to life with just a little extra work by parents or crafty teens.

Make your kid the star of the costume party with this scuba diver outfit this year.

It’s all made from everyday items and totally customizable to match the child’s tastes.

These DIY Little Mermaid costumes are designed for people who aren’t master seamstresses.

The simple tips and tricks will help convert the whole family into characters from the beloved cartoon.

This adorable puffer fish costume is sure to stand out on the 31st.

The body is made with paper maché over an exercise ball. The spikes are dense craft foam and the eyes are Styrofoam.

Any little marine biologist in training will love this option.

By Alpha Mom

Made with cardboard, this sea shell costume is simple and no muss, no fuss.

But it’s still adorable and perfect for any beach loving kid come Halloween.

by The Creative Heart Studio

This sea anemone costume looks wild and creative and is sure to turn some heads.

Plus, it’s way simpler to put together than it looks.

by Instructables

While most people won’t ever get this close to a shark, it still makes a great costume.

The man-eating shark costume is a funny and eye-catching way to dress up this Halloween.

Kids will have a bubbly good time dressed as an underwater explorer surrounded by vibrant sea life.

And to make that reef pop with even more color and texture, you can use my easy coral reef decoration tutorial to build a show-stopping backdrop right into the costume!

Grab some red clothes to layer under this surprisingly simple lobster outfit.

Several empty boxes, some red paint, and a free afternoon are about all it takes.

Another great option for Halloween is this full-body seahorse outfit made with foam mats.

While it does take some work, the end result speaks for itself.

Here’s a two-for-one option for kids this Halloween.

The narwhal costume is adorable, and their little jellyfish friend is actually a bag, perfect for carrying candy.

What kid isn’t in love with dolphins?

These adorable sea creatures make an inspired costume choice for some Trick-or-Treating .

Find a big cardboard box and get to work!

by Costume Works

We all know the song, and chances are the kids are obsessed with it.

Have your own little baby shark with a super cute kids shark costume.

You will need some sewing skills and time for this one, but it's all so worth it.

For the most ocean-tastic costume ever, why not be the actual ocean?

It’s simple to put together with some basic costume materials and guaranteed to be a unique outfit for Halloween

Another costume that will take some patience to make but oh so cute.

Unfortunately this one comes with no instructions.

I did find another starfish costume with instruction but no good pictures.

But it's worth checking it out.

Costume designers rejoice, because this adorable pattern will have kids clapping all 8 hands in delight.

The link will take you to an Etsy pattern for the cutest octopus costume ever.

Mermaids are great, but sometimes their fins get all worn out.

This seahorse mount is the perfect way for a little mermaid to take a rest while out collecting candy.

Here’s a fairly quick and simple under-the-sea costume idea.

This DIY sea turtle was made with only cardboard and paint