Under the Sea Birthday Party: 12 Tips for a Charming Celebration

Planning a birthday party is an exciting challenge, and the possibilities are endless when you are planning an Under the Sea birthday party. Whether you’re throwing a bash for your little one, a teen, or an adult who loves all things aquatic, this theme offers the perfect balance of creativity, adventure, and fun. From vibrant marine creatures to shimmering ocean waves, this guide will walk you through how to plan a magical Under the Sea birthday party that will leave guests talking for months.

1. Set the Date and Budget

Before you dive into the details, the first step in planning your Under the Sea birthday party is setting the date and budget. Choose a date that works well for the birthday person and consider giving yourself at least a month of prep time. Once you’ve picked the date, determine how much you’re willing to spend.

Break down your budget into different categories:

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Venue
Decorations
Invitations
Food and drinks
Entertainment
Party favors

Having a set budget will help you avoid overspending and make smart decisions when it comes to planning.

2. Choose the Perfect Venue

The location of your Under the Sea birthday party sets the tone for the event. If you’re hosting a small gathering, your home or backyard might be perfect. However, for larger crowds or a more elaborate setup, consider renting a space like a community center, beach club, or even an aquarium!

When choosing the venue, consider:

Size of the guest list: Make sure the space can comfortably accommodate your guests.
Weather: If you’re planning an outdoor party, check the forecast and have a backup plan in case of rain.
Accessibility: Ensure the venue is easy for guests to reach.

3. Send Creative Under the Sea birthday party Invitations

Your invitations set the stage for the theme, so make sure they are as fun and vibrant as the Under the Sea birthday party will be. You can create digital or physical invitations with an “Under the Sea” theme. Some fun ideas include:

Message in a bottle: Send mini bottles with rolled-up invites inside.
Ocean-themed designs: Include sea creatures, waves, or bubbles on the invite.
3D pop-up cards: Guests will love the surprise of a sea turtle or a fish jumping out of the card.

Don’t forget to check out our collection of templates that are free to download and easy to edit and print to help your birthday invites preparations.

Don’t forget to include all the essential details:

Date and time
Location and directions
Dress code (e.g., “Come in your favorite aquatic costume!”)
RSVP

4. Dive into Under the Sea birthday party Decorations

Transform your venue into a magical underwater world with the right decorations. Use a mix of blue, green, and turquoise colors to mimic the ocean’s natural hues. Here are some creative ideas to get you started:

Underwater backdrop: Use blue streamers, balloons, or fabric to create a wall of “water.” Add seaweed cutouts, fish, and bubbles to bring it to life.
Balloon garlands: Create garlands in various shades of blue, white, and green to resemble waves or bubbles.
Hanging jellyfish: Craft jellyfish from paper lanterns and streamers for a floating effect. Hang them from the ceiling to make it feel like you’re under the sea.
Netting and sea creatures: Drape fishnet around the room and attach plush fish, starfish, and crabs.
Mermaid tail props: If mermaids are part of your theme, include large mermaid tail cutouts for a whimsical touch.
Light and sound effects: Use soft blue lighting to create an underwater ambiance, and play the sounds of ocean waves in the background.

Under the Sea birthday party decorations via Catch My Party

5. Ocean-Inspired Costumes

Encourage your guests to dress up to match the theme. Some costume ideas include:

Mermaids and mermen
Pirates
Sea creatures (like sharks, dolphins, or jellyfish)
Beachgoers or scuba divers

You can also provide simple costume accessories like shell necklaces, pirate hats, or mermaid crowns to give guests who may not come in costume something fun to wear.

6. Under the Sea birthday party Menu Ideas

Your menu is a chance to get creative with ocean-inspired foods. Incorporate both seafood and sea-themed dishes, but make sure to have options for all dietary needs. Here are some fun ideas:

Seafood platters: Shrimp cocktails, crab cakes, or sushi rolls.
Fish-shaped sandwiches: Use cookie cutters to shape sandwiches for kids.
Starfish cookies: Decorate star-shaped cookies with icing and sprinkles.
Clam shell sliders: Mini sliders with buns shaped like clam shells.
Ocean punch: Blue punch with floating “icebergs” (scoops of vanilla ice cream).
Coral reef veggies: Arrange carrots, cucumbers, and bell peppers in the shape of a coral reef.
Seaweed snacks: Nori chips or veggie strips can be a fun seaweed-themed treat.

Don’t forget a showstopping cake! Whether it’s a mermaid tail cake, a coral reef design, or a simpler seashell-topped cake, make sure it fits your theme. Cupcakes decorated with fish or jellyfish toppers are also a great option.

Under the Sea birthday party food via Tidy Mo

7. Ocean-Themed Games and Activities

To keep your guests entertained, plan games and activities that tie into the underwater theme. Don’t forget to also prepare small prizes for the winners of each game, keep the games short and fun, and if your party guests are little children, be ready to improvise and just go with the flow! For an Under the Sea birthday party, here are some ideas for various age groups:

Treasure hunt: Set up a pirate-themed treasure hunt where guests search for hidden “treasure” (candy or small prizes).
Pin the tail on the mermaid: A fun twist on the classic “Pin the Tail on the Donkey.”
Shark ring toss: Create a cardboard shark head and toss rings onto its “teeth.”
Underwater limbo: Use a pool noodle as the limbo stick and play ocean-themed music as guests go under the “wave.”
Aquarium tour: If your venue is an aquarium, arrange for a private tour or a meet-and-greet with a marine biologist.
Craft station: Let guests make their own fish hats, shell necklaces, or decorate treasure chests.

8. Party Favors to Make a Splash

Send your guests home with Under the Sea birthday party favors that will remind them of their time under the sea. Some ideas include:

Seashell necklaces or bracelets
Ocean-themed stickers or temporary tattoos
Mini beach toys (like sand molds or buckets)
Sea creature plush toys
“Under the Sea” coloring pages
Personalized treasure chests filled with candy or small toys

You can even have a DIY station where guests decorate their own goody bags or treasure chests.

9. Photo Opportunities

Create Instagram-worthy moments by setting up a themed photo booth. Photo booth is also such a great way to encourage your Under the Sea birthday party guests to take a lot of photos to keep as mementos of the good time that you had. Some ideas for a fun “Under the Sea” backdrop include:

A life-size mermaid tail: Let guests “become” a mermaid by posing with a large, stand-up tail prop.
Cardboard submarine: Guests can pretend to be explorers in a photo prop submarine.
Bubble machine: Capture magical underwater moments with a bubble machine creating the illusion of floating bubbles in the air.
Ocean creatures cutouts: Pose with giant cutouts of sharks, dolphins, or sea turtles.

Provide props like snorkels, pirate hats, and seashell crowns for guests to wear in their photos.

10. Music to Set the Mood

The right music can enhance the underwater atmosphere. Create a playlist of ocean-inspired songs or sounds to keep the theme alive throughout the party. Hare are some great songs to include to your Under the Sea birthday party playlist:

“Under the Sea” from The Little Mermaid
“Beyond the Sea” by Bobby Darin
“Octopus’s Garden” by The Beatles
Whale sounds or ocean wave soundtracks

If you want to go all out, hire a live band to play beach or island-themed tunes, or set up karaoke for guests to sing their favorite ocean songs.

11. Capture the Magic with a Photographer

Hiring a photographer to capture all the special moments of your Under the Sea birthday party can be a great investment. If your budget allows, consider booking a professional who can take photos throughout the event. Alternatively, you can designate a friend or family member to act as the official photographer, or set up disposable cameras around the venue for guests to use.

Under the Sea birthday party stage. Credit Party Dish Event Styling

12. Plan for Clean-Up

After the fun has ended, you’ll need a plan for clean-up. If you’re hosting at home, recruit a few friends or family members to help. Renting a venue? Ask about their clean-up policy beforehand so you’re prepared. It’s also a good idea to have trash and recycling bins conveniently located throughout the party space.

Conclusion

Planning an Under the Sea birthday party is an exciting and creative process that offers endless opportunities to make the event magical. From thoughtful decorations to a themed menu, fun activities, and memorable favors, every detail contributes to creating an unforgettable experience. Follow these tips, and your guests will feel like they’ve been transported to an underwater adventure they’ll never forget.

Happy planning, and may your Under the Sea birthday party be filled with joy, laughter, and a splash of fun!