How do you make an easy DIY ocean costume?

The easiest DIY is a jellyfish. Take a clear dome umbrella, tape colorful ribbons and bubble wrap strips to the inside rim to act as tentacles, and wear a matching solid-colored outfit underneath.

What should I wear for a school Ocean Day?

Wearing solid blue clothing is the simplest way to participate. You can easily upgrade this by pinning paper cutouts of fish, starfish, and seaweed to your shirt.

How do you make a DIY scuba diver costume?

Paint two plastic soda bottles silver or bright green, tape them together with black duct tape, and attach elastic straps to wear them like a backpack. Pair this with black clothing and a snorkel mask.

AI-generated example

Ocean Themed Costumes

Make a splash with creative, easy-to-make under-the-sea looks.

Ocean themed costumes are a popular choice for Halloween, school events, and parties because they offer endless creative possibilities. Whether you want to transform into a glowing jellyfish, a deep-sea scuba diver, or a classic mermaid, these looks are highly customizable and fun to wear. This guide covers how to plan, assemble, and style a variety of marine-inspired outfits.

Difficulty: Easy
Time: ~45 min
Budget: $15–75

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40 Ocean Themed costume ideas

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What you need for a Ocean Themed Costumes costume

Monochromatic base layer
A solid-colored bodysuit, leggings, or t-shirt matching your chosen sea creature (e.g., blue for water, pink for jellyfish, gray for a shark).
DIY: Use a plain t-shirt and matching sweatpants from your closet.
Amazon
Clear dome umbrella
A transparent bubble umbrella used as the structural base for a DIY jellyfish costume.
Amazon
Ribbons and mesh trim
Assorted iridescent ribbons, yarn, and deco mesh to hang from the umbrella to mimic jellyfish tentacles.
DIY: Cut strips of old plastic tablecloths or bubble wrap.
Amazon
Battery-operated LED fairy lights
Waterproof, battery-powered micro LED string lights to weave inside the umbrella or attach to your outfit for a bioluminescent glow.
Amazon
Cardboard or foam sheets
Sturdy crafting materials to cut out shark fins, crab claws, or starfish shapes to attach to headbands or waist straps.
DIY: Upcycle clean shipping boxes and paint them with acrylics.
Amazon
Scuba goggles and snorkel
A classic plastic snorkel mask set to instantly create a scuba diver or marine biologist look.
DIY: Cut a swim goggle shape out of black felt and wear it over your forehead.
Amazon

How to put it together

1
Choose your specific ocean concept, such as a glowing jellyfish, a scuba diver, or a shark.
2
Put on your solid-colored base layer to establish the main color palette of your sea creature.
3
If making a jellyfish, open the clear umbrella and tape or tie lengths of ribbon, yarn, and deco mesh along the rim to create hanging tentacles.
4
Weave battery-operated LED fairy lights inside the dome of the umbrella, securing the battery pack near the handle with tape.
5
If going as a scuba diver, paint two empty two-liter soda bottles silver, tape them together, strap them to your back like oxygen tanks, and put on your snorkel mask.
6
Add finishing touches like a shark fin headband, crab claw gloves, or seashell jewelry depending on your chosen theme.

Makeup & hair

Keep hair sleek and wet-looking using hair gel, or spray temporary blue or green hair color. Use shimmering, iridescent highlighter on the cheekbones and temples to mimic the glistening surface of the water.

Ocean Themed Costumes for couples, groups, kids & more

couples: Go as a Shark and a Scuba Diver, or a Mermaid and a Sailor.
group: Create a full school of fish, a coral reef ecosystem, or a group of glowing jellyfish in different colors.
kids: A simple blue t-shirt with felt fish glued on makes an easy 'ocean' outfit, or use a gray hoodie with a felt fin sewn to the back.
Plus size: A flowing, oversized blue or teal poncho decorated with felt sea creatures offers a comfortable, breezy fit.
pet: A simple shark fin harness or a red crab costume with soft plush legs.

Tips

If carrying a jellyfish umbrella, make sure the hanging ribbons are cut short enough that you won't trip on them.
Use safety pins to secure heavy foam attachments, like shark fins or crab claws, to your clothing.
Keep battery packs for LED lights easily accessible so you can turn them off to save power during the day.
For outdoor nighttime events, the glowing jellyfish or bioluminescent sea creature options provide excellent visibility and safety.

Ocean Themed Costumes costume FAQ

How do you make an easy DIY ocean costume?: The easiest DIY is a jellyfish. Take a clear dome umbrella, tape colorful ribbons and bubble wrap strips to the inside rim to act as tentacles, and wear a matching solid-colored outfit underneath.
What should I wear for a school Ocean Day?: Wearing solid blue clothing is the simplest way to participate. You can easily upgrade this by pinning paper cutouts of fish, starfish, and seaweed to your shirt.
How do you make a DIY scuba diver costume?: Paint two plastic soda bottles silver or bright green, tape them together with black duct tape, and attach elastic straps to wear them like a backpack. Pair this with black clothing and a snorkel mask.

Did you know? World Ocean Day is celebrated annually on June 8th, which is why ocean-themed costumes are popular year-round for educational school events as well as Halloween.