Planning a mermaid birthday party? You’re in the right place, friend.
Whether you’re going big with balloon arches and a cake that’s almost too pretty to cut — or keeping it simple with a few sparkly touches and some bubbles in the backyard — you don’t have to be a professional party planner to make it magical.
This guide is packed with easy, doable ideas to help you throw a mermaid party your little one will absolutely love.
From cute decorations to food, games, and more — think of this as your “plan it like a mom, pull it off like a pro” cheat sheet.
Mermaid Birthday Party Themes by Age (First Birthday and Beyond)
One size definitely doesn’t fit all — here’s how to tailor your mermaid birthday party theme to your child’s age and style!
1st Birthday: One-der the Sea
Celebrate your little one’s big milestone with soft pastels, seashells, iridescent sparkle, and sweet mermaid touches perfect for a magical first birthday.
2nd Birthday: Making Waves at Two
Bright, bubbly fun! Lean into ocean waves, bubbles, and playful mermaid elements.
Lots of teal, blue, and shimmer — plus bubble machines and beach ball games for extra fun.
3rd Birthday: Shell-abrating Three!
Turn up the color!
Add bold purples, teals, and corals with lots of bubbles, glitter, and playful games.
4th Birthday: Fintastic Four
Kids love interactive fun at this age — set up crafting stations like DIY mermaid crowns or “build a shell necklace” tables.
5th Birthday: Five and Fabulous
Glam it up with metallics, sparkly face paint, and fancy under-the-sea decor to make your five-year-old feel extra fabulous.
6-8 Years: Mermaid Makeovers & Adventures
Think spa stations (mermaid hair glitter or nail polish), treasure hunts, scavenger challenges, and even mini dance parties with a bubble machine!
Mermaid Birthday Party Decorations (DIY and Easy Ideas)
Make your party space feel like a real underwater wonderland with these fun and easy mermaid birthday party decorations!
Balloon Arches: Use pastels, blues, and iridescent balloons to create a flowing, ocean-like backdrop.
Shimmering Backdrops: Hang sequin curtains or DIY a tulle backdrop to give that underwater shimmer effect.
Ocean Floor Tables: Drape gauzy blue tablecloths and scatter faux shells, pearls, and sand dollars.
DIY Jellyfish Lanterns: Hang paper lanterns with long ribbons and streamers to look like floating jellyfish.
Bubble Magic: Use bubble machines for an extra magical effect (kids will love it).
Personalized Signs: Think “Welcome to [Child’s Name]’s Under the Sea Adventure!”
Mermaid Birthday Party Food Ideas (Snacks and Treats)
Make your food table a feast for mermaids and pirates alike with these colorful and fun mermaid birthday party food ideas!
Mermaid Tail Cookies: Sugar cookies shaped like tails, decorated with pastel icing and edible glitter.
These look gorgeous on a dessert table and double as a sweet party favor!
Under the Sea Cupcakes: Top cupcakes with blue and teal frosting swirls, then add candy pearls, sprinkles, or mini fondant shells for the perfect ocean touch.
Ocean Jello Cups: Layer blue Jello with whipped cream “waves” and hide gummy fish or ocean-themed candy inside for a fun surprise.
Sea Water Punch: Make a batch of blue raspberry lemonade and float Swedish Fish or gummy rings in clear cups for a fun, ocean-themed party drink.
Quick Tip: Label your food with cute signs like “Seashell Snacks” or “Coral Crunch” to add extra under-the-sea charm!
Fun Mermaid Birthday Party Games and Activities
Pick a few splash-tastic activities to keep little mermaids laughing and moving!
Seashell Treasure Hunt: Hide plastic seashells filled with candy or tiny treasures around the party area for kids to find.
Easy to set up, and kids of all ages love it!
DIY Mermaid Crowns: Set up a simple craft table with headbands, pearls, shells, and gems.
Kids can create their own sparkling mermaid crowns — a fun activity and a take-home favor!
Bubble Dance Party: Crank up the music and set up a bubble machine for an unforgettable under-the-sea dance party.
Perfect for toddlers and big kids alike!
Bonus Tip: If you have a wide range of ages at the party, set up a few different “activity zones.” Little ones love simple games like a bubble dance party, while bigger kids might enjoy a treasure hunt or craft station. That way everyone stays happy — and you get a little breather too!
➡️Want even more ways to make your outdoor celebration easy and fun? Check out my best tips for hosting an outdoor kids birthday party here!
Mermaid Birthday Cakes (Ideas for a Magical Party)
Whether you go simple or show-stopping, these mermaid birthday cakes will make a splash!
Ombre Wave Cake: Frosted in shades of blue, teal, and purple to look like swirling ocean waves.
Or go with a beachy look!
This ocean-inspired cake with sandy crumbles and fondant seashells brings total seaside vibes — perfect if you want something coastal and creative without going too sparkly.
Mermaid Tail Topper Cake: A simple cake with a glittering fondant mermaid tail sticking out of the top.
This fun sprinkle-covered cake with a teal fondant tail is another favorite — playful, vibrant, and full of under-the-sea charm!
Make it Even More Magical: Top the cake with a custom topper that says “[Name] is One-der the Sea!” for first birthdays.
One-der the Sea: Mermaid First Birthday Party Ideas
Throwing a first birthday? Here’s how to make your One-der the Sea mermaid party unforgettable:
Smash Cake: A mini ombre-frosted cake just for baby — top it with a fondant mermaid tail, tiny shells, or a sprinkle of edible glitter.
Highchair Decorations: Deck out the highchair with a “One-der the Sea” banner, pastel balloons, and pearl garlands hanging down the sides.
Photo Moments: Set up a mini underwater-themed backdrop — think soft blues, purples, and a big “One-der the Sea” sign for milestone photos.
Birthday Outfit: Adorable options include a seashell-printed onesie, a tutu in ocean colors, or even a tiny mermaid tail skirt.
Quick Tip: If you want cute (but stress-free) photos, set up your photo backdrop before guests arrive — baby’s patience is usually best early in the party!
Bonus Tips for a Splash-Tastic Mermaid Birthday Party
Make your mermaid birthday party even more magical with these easy bonus ideas! Perfect for keeping the fun flowing and making memories your little one will treasure.
Create a Dress-Up Station: Stock it with mermaid tails, crowns, and ocean animal costumes.
Real Mermaid Appearance: Consider hiring a professional mermaid performer for a jaw-dropping moment!
Under the Sea Playlist: Make a playlist of ocean-themed songs (bonus if you sneak in “Under the Sea” from The Little Mermaid).
Eco-Friendly Touch: Use reusable decor like fabric banners and washable shells to stay green and save money.
You’ve planned the games, the food, the decorations — now it’s time to zoom out and focus on the big picture: creating a day full of joy, magic, and memories your little one will never forget.
Make Your Mermaid Birthday Party Unforgettable
At the end of the day, it’s not about having the biggest balloon arch or the fanciest cake.
It’s about celebrating your little one and creating moments you’ll both remember forever.
Whether you throw a backyard bash with bubbles or a full-blown under-the-sea adventure, your love and joy will be the real magic.
You’ve got this, mama. Now — let’s dive in and make some mermaid memories!