57 Stunning Under The Sea Birthday Party Ideas

Photo: Green Envelople

An under the sea birthday party is a fantastic theme for boys and girls of all ages. With under the sea decorations, invitations, food ideas, and party favors in abundance, you’ll have no issue putting together the ultimate under the sea party.

To make your party planning as straightforward as possible, I’ve put together some of the best under the sea birthday party ideas so you have everything you need all in one place. So, with that being said, if you’re getting ready to plan your little one’s next party, keep on reading!

Theme Ideas For An Under The Sea Birthday Party

Before starting your under the sea birthday party planning, I’ve found it’s best to create a rough plan of the colors and elements you can include in your party that ties into the under the sea theme.

First up, let’s talk about colors. You can opt for a few different colors for an under the sea party. However, blue, green, and a sandy shade of yellow will be the three you mainly focus on. Blue, of course, for the ocean, green for seaweed and other underwater vegetation, and yellow for the sand at the bottom of the sea. Additionally, you can include pink, orange, purple, and red in your theming to represent sea anemones and underwater animals. 

Next, you’ll need to consider the different elements to include in your decorations and food ideas. For example, if you have a little girl celebrating her birthday with an under the sea party, you may want to include mermaids and pretty shells. But if you have a boy celebrating his birthday, then (friendly) sharks and other underwater animals may be better suited to him. 

Venue

With an under the sea theme, there are no better venues than a swimming pool or a beach. But of course, if a pool or a beach isn’t an option, you can also decorate your home, garden, or a local hall to create a beautiful under the sea setting that your little one will love. 

Under the Sea Party Invitations

The best way to get your guests excited for your under the sea birthday party is to send out invitations with the under the sea theme. When it comes to invitations, you have the choice of traditional hard copy invites that you’ll need to hand out or mail to your guests, or you can opt for customizable and downloadable invites that you can send digitally to cut back on costs and lower your impact on the environment.

Depending on whether you’re opting for the standard under the sea theme or an under the sea theme, including mermaids, I’ve found two different traditional paper copy invites that would work particularly well. 

Firstly, these Mermaid Tail Under the Sea Invites are absolutely adorable, and they tie in your three primary focus colors, as well as purple, making them a perfect match for a mermaid under the sea theme. 

Secondly, I love these Animal Inspired Under the Sea Invites as they’re simple, beautifully illustrated, and feature a selection of sea animals that will pop up elsewhere in your party’s decorations and food ideas. 

If you’re instead sending out digital invitations to your friends, I love this Editable Mermaid Under the Sea Invites and this Editable Animal Under the Sea Invites. Digital invites are simple; you only need to edit the text on the invites, download the file, and email/text it to your friends. Of course, you can print the invites out and hand them out the traditional way, but the choice is entirely up to you! 

Under the Sea Party Supplies and Decorations

For me, ordering all the decorations for the party is the most exciting part, as you can begin to see the theme coming together. You can obviously purchase as many decorations as you wish, but there are also some ways to keep costs low by DIYing your own under the sea decorations, which I’ll get more into later. 

Balloons

You can’t have a party without balloons, and there is no better way to incorporate your under the sea theme than by putting together a balloon arch. And don’t worry, I know what you’re thinking. Balloon arches are actually incredibly easy to put together, especially if you purchase an arch kit and have a balloon pump. 

For mermaid inspired under the sea themes, this Mermaid Balloon Arch comes together as a mermaid’s tail and ties in your focus colors of blue, green, and purple. Alternatively, if you’re choosing a more generic under the sea theme, this Blue Under Water Animal Balloon Arch equipped with eight underwater animal foil balloons will work perfectly. 

If you want to add a few extra balloons to your venue, you could also purchase these Foil Sea Animal Balloons that your guests could take home as party favors. 

Banner

Next on your decorations list is a banner that you can hang under your balloon arch or completely separately in a different part of the venue. For generic under the sea themes, this Happy Birthday Sea Animal Banner incorporates a range of sea animals like octopuses, lobsters, and jellyfish. 

Under the sea parties leaning towards a mermaid theme, however, can instead display this Happy Birthday Mermaid Banner that ties in your theme colors and measures 12 feet long. 

Backdrop

If you plan on having your under the sea party at a large venue, then a backdrop like this Under the Sea Backdrop is a great way to fill up some empty space while also providing a photo opportunity for guests and the birthday child. 

Tablecloth, Cups, and Plates

To finish off your decorating, be sure to grab an Under the Sea Tablecloth, Cups, Plates, and Napkin Set so your guests have something to eat with and off during the party.

DIY Decorations

If you consider yourself relatively crafty, then there are a few different under the sea birthday party ideas and decorations you can DIY to suit your under the sea theme. 

Hanging Jellyfish

Hanging jellyfish, as seen on Arts and Crackers, is a relatively simple DIY decoration that only requires a few supplies. The Arts and Crackers website focuses on white jellyfish, but you can opt for colored jellyfish if you wish by using some paint and different colored ribbon. 

Shark Head Photo Booth

A shark head photo booth is a great DIY option as it doubles up as a venue decoration and a photo opportunity for guests attending the party. 

Julie Jimenez created this shark head photo booth below, and it’s an excellent reference. You could create the shark out of cardboard or foam, making it as big or as little as you like! 

Pool Noodle Coral Reef

Head down to the dollar store and grab some brightly colored pool noodles that you can transform into your very own coral reef. For this project, you’ll also need a cardboard box, a box cutter, wire hangers, a pair of pliers, and glue, but these should all be easily accessible and affordable. 

This Youtube video by That Lovely Feeling has excellent step-by-step instructions on how to put together your pool noodle coral reef.

Under the Sea Activities and Games

During your under the sea party, you can play classic party games such as musical statues, musical chairs, and pass the parcel, and you can also throw in some under the sea inspired games to go along with your theming. 

Temporary Under the Sea Tattoos

I don’t know what it is, but kids love temporary tattoos. These Under the Sea Temporary Tattoos are easy to apply as you simply dab them with a wet towel. With so many animals in different colors, each child is guaranteed to find a temporary tattoo to suit them. 

Pin the Fin on the Shark

We’ve all played pin the tail on the donkey, but donkeys don’t live under the sea, so your party guests can play Pin the Fin on the Shark instead. The rules are exactly the same. Blindfold the child, spin them 3 times, give them a fin, and see how close they can get to the shark’s correct fin position! 

Ocean Animal Bean Bag Toss

Bean bag toss is one of those games that you don’t realize how fun it is until you play. With this Ocean Animal Bean Bag Toss, your guests can battle it out for the highest score to see who has the best hand-eye coordination. 

How Many Fish Are In The Sea?

For this game, you’ll need a jar (any jar will do, the size is up to you) full of fish sweets, such as Swedish Fish or Smart Sweets. The aim of the How Many Fish Are In The Sea? Game is for your guests to guess how many fish are crammed into your jar. The person with the closest score wins the entire jar!

Under The Sea Pinata

Pinatas have always been a fun party game, and with an under the sea theme, you have numerous pinata options to choose from. Some of my favorites include the following:

Under the Sea Food and Drinks

You don’t necessarily need to serve food at your party, especially if you time it right after breakfast or lunch. However, if you do want some snacks for your guests to eat, here are some under the sea themed snack ideas that are relatively easy to make. 

• Oyster Pearl Cookies – Two cookies, some pink frosting, and a pearl candy create these adorable Oyster Pearl Cookies that are perfect for an under the sea party.
• Ocean Dipped Pretzel Rods – Coat a pretzel stick in blue-dyed white chocolate and add sprinkles to finish. 
• Ocean Blue Lemonade Popsicles – Popsicles are an ideal snack for an under the sea themed party in the middle of summer!
• Under the Sea Cupcakes – Cupcakes are easy to make, and with a few under the sea cake toppers, they’ll be under the sea themed in no time!

Under the Sea Birthday Party Cake Idea

When I’m stuck on a cake idea for a birthday party, I always head to Pinterest as there are hundreds of under the sea birthday party cake ideas for you to recreate or have a local bakery recreate. 

Themed Gift Ideas

If I can, I like to purchase a gift for the birthday child in the same theming as the party. With an under the sea theming, there are a few different gifts you can choose from, with my favorites being the following: 

10. If there is a local aquarium near the birthday child’s house, then you could consider a voucher/IOU for an aquarium pass.

Outfit for the Birthday Child

The possibilities of an under the sea outfit for the birthday child are endless. You can purchase a simple Under the Sea Themed Dress or some Under the Sea Themed Shirt and Shorts, or you can channel your child’s favorite under the sea Disney character with a Sebastian T-shirt, a Finding Nemo T-shirt, or a Little Mermaid T-shirt.

Under the Sea Birthday Party Favor Ideas

If you like to send your guests home with party favors and a slice of cake, these Under the Sea Party Bags are perfect for filling.

Some under the sea birthday party favor ideas include: 

Thank you Cards

Once the party is over and your child has opened all their gifts, it’s time to then send out your thank you cards, which again, like your invitations, you can send out as a traditional paper copy thank you card, or you can customize and download thank you cards digitally which you can then email over to your guests. 

I’ve found two beautiful under the sea themed paper copy thank you cards, the first being Watercolor Under the Sea Animal Thank You Cards and the second being these Aqua Blue Ocean Thank You Cards.
For downloadable thank you cards, I think these Sea Creature Under the Sea Thank You Cards are beautiful and perfect for both boys and girls.

Conclusion

I hope these under the sea birthday party ideas have helped you create the ultimate under the sea party for your little one!