Under the sea parties are fun for every age. Mermaids, sharks, octopus, and shells give you lots of ways to decorate.
Every idea here comes from a real party posted on Instagram by party decorators across the US. No AI pictures, only real setups you can copy or book.
Under each post you get a short breakdown and a quick tip. Tap the heart on your favorite idea, and the most loved ones move to the top.
Love mermaids? See our mermaid birthday party ideas.
1. Build a Giant Balloon Octopus
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Post by @believeindreamcreations, Cincinnati, OH
This balloon octopus went viral, and it is easy to see why.
This Ohio setup has a giant blue balloon octopus, sea creatures, coral, and a teal backdrop. It is the star of the party.
- Ask a balloon artist for an octopus.
- Add starfish and coral props.
- Use teal and blue colors.
🎨 Ocean colors
Blue and teal with coral look like the sea.
2. Throw a ONEder the Sea Party
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Post by @freckled__fun, Chesapeake, VA
A cute pun for a first birthday.
This Virginia setup has a big clam shell, pastel balloons, starfish, and pearls. It is soft and pretty for a baby girl.
Use a clam shell as a photo seat.
3. Add Mermaid Magic
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Post by @letsgetpoppinandco, Visalia, CA
Mermaids make any sea party magical.
This California setup has a purple arch with her name, a big pink shell, and pastel balloons in pink, purple, and green.
- Pick pink, purple, and teal.
- Add a big shell prop.
- Give mermaid tail blankets as favors.
Quick tip
Shell shaped plates and pearl necklaces make easy mermaid details.
4. Plan a Little Mermaid Party
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Post by @vysual_decor, Bay Area, CA
Ariel fans will love this one.
This California setup has Ariel art, a coral reef, a rainbow balloon garland, and a big number. It looks like a scene from the movie.
Play Little Mermaid songs during the party.
🎨 Ariel colors
Bright sea colors match the movie.
5. Make Waves With a Sequin Wall
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Post by @decoballoons.usa, Atlanta, GA
Sparkly blue sequins look like water.
This Georgia setup has a blue sequin wall, a mermaid tail, and purple and pink balloons with clear bubble balloons.
- Rent a sequin wall.
- Add clear balloons as bubbles.
- Hang a mermaid tail prop.
Sparkle setup list
6. Go Full Ariel With Coral
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Post by @pinkfestco, San Diego, CA
Coral and Ariel make a dreamy mix.
This California setup has a pink panel with Ariel, purple coral pieces, Flounder, and pink and teal balloons.
Purple coral props can be cut from foam board.
📸 Ariel party plan
Set the panel.
Add coral props.
Place sea friends.
Cut the cake.
7. Set an Under the Sea Table
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Post by @bloomanddecor, Orange County, CA
A pretty table makes the party feel complete.
This California setup has a long table with shell plates, pastel decor, and a big sea backdrop with balloons.
- Use shell shaped plates.
- Add pearls down the table.
- Pick soft blue napkins.
Use shell plates
Add pearls
Keep colors soft
Too many colors
Sharp decor for kids
No seating plan
8. Celebrate Two Kids by the Sea
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Post by @lizs_poppin_creations, Royal Oak, MI
This setup was made for two siblings at once.
This Michigan setup has a white panel that says One and Three by the Sea, with shells, starfish, and pastel balloons.
A double party saves time and money.
9. Try a Shark Party
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Post by @jametheballoonco, Menifee, CA
Sharks are a big hit with boys.
This California setup has a blue tent, a shark panel with names, and navy, blue, and silver balloons. It looks cool and fun.
- Use navy and light blue.
- Add shark fin props.
- Serve blue jello cups.
🎨 Shark colors
Navy and blue look like deep water.
10. Add Baby Shark
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Post by @balloonsbysandraa, Rosedale, MD
Toddlers love Baby Shark.
This Maryland setup has a blue panel, colorful shark family cutouts, seaweed balloons, and bright red, yellow, and blue balloons.
Play the song for a dance party.
Quick tip
Baby Shark works best for 1 to 3 year olds. Keep the party short and sweet.
11. Plan a Shark Sighting Party
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Post by @thatballoongirlhtx, Houston, TX
Warning: shark sighting.
This Houston setup has hanging blue fringe like waves, shark balloons, and blue and green balloons over the table. It feels like being underwater.
- Hang blue fringe from the ceiling.
- Add shark balloons.
- Use a blue tablecloth.
Underwater room list
12. Choose a Pinkfong Setup
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Post by @craftymomsla, Inglewood, CA
Pinkfong and Hogi are toddler favorites.
This California setup has a pink and purple balloon garland, a panel with Pinkfong friends, and ocean details. It is bright and cute.
Pick 2 main colors to keep it neat.
FAQs
What do you need for an under the sea party?
Blue and teal balloons, shells, starfish, sea creature props, and a backdrop with fish or mermaids.
What colors are best for an under the sea theme?
Blue, teal, and white for water, plus coral, purple, or pink for sea life and mermaids.
What food can I serve at an under the sea party?
Fish crackers, blue jello cups, shell pasta, and ocean cupcakes are easy and fun.
Is under the sea good for boys and girls?
Yes. Use mermaids and pastels for girls, or sharks and navy for boys. For a winter theme, see our Frozen party ideas.
Final Thoughts
An under the sea party is colorful, fun, and easy to customize. Pick one idea from this list, use the tip under it, and choose mermaids, sharks, or both. Want more themes? See our Bluey birthday party ideas, and pin this list to Pinterest.
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