12 Unique Under The Sea Party Ideas (2024)

Are you planning a party for a little one who can’t get enough of mermaids, sand castles, and sea creatures? You’ll want to see these 12 unique under-the-sea party ideas that are sure to make a splash!

While you’re searching through this deep-sea treasure trove of tips, look out for some of the relevant Peerspace listings we’ve included. Peerspace is the largest online marketplace for hourly venue rentals and makes it easy to discover and rent hidden gem spaces near you. Many of which happen to be under-the-sea party-worthy, as you’ll soon see. So put on your snorkel and let’s dive right in!

1. Mimic swimming creatures with paper lanterns

A clever way to have some underwater visitors to your party that aren’t balloons is by using paper lanterns. These mermaid party jellyfish lanterns from Party Treasure Co. on Etsy can give you an idea of what we mean. Stringing a few of these up will make it look like swimming jellyfish are passing through your party! Or, if you’re feeling crafty and want to make your own, this tutorial for adorable fish paper lanterns is a great alternative and a fun little project.

2. Use a backdrop for your centerpiece

Having a backdrop for your centerpiece is one of those under-the-sea party ideas that will provide a golden photo opportunity for you and your guests. There are tons of amazing options out there for all budgets. If you prefer one for less than $5, this easy DIY mermaid backdrop from Tikkido.com can’t be beat. Or, you can go all out with something like this coral reef wood cutout from The Wood Shop Guy’s Etsy page. Check out the colorful balloon arch that makes for a cute accent!

Set up these sea treasures at a Peerspace event venue that has all the ocean ambiance you can ask for. This modern beach house on the sand in Aptos, CA is just one of the many options out there!

3. Throw the ultimate pool party

The best kind of under-the-sea party is definitely going to include swimming. Find all the best mermaid or pirate inflatables and fill your pool to create your own little ocean.

Don’t have a pool of your own? Don’t worry, Peerspace can connect you with some of the most amazing pool party venues across the globe. Take for example this party, pool, and lounge space in Tomball, TX. This is the ultimate destination for anyone trying to throw a pool party. Search your own area and see what kind of backyard oases are hidden in your neck of the woods!

Check out these toddler birthday party ideas to celebrate your littlest pirate!

4. Get creative with shark gummies and Swedish Fish

Everyone’s favorite oceanic candies have to be Swedish Fish and shark gummies! Use that to turn them into some unique under-the-sea party ideas. We love these ocean blue lemonade popsicles from Play Party Plan. They’re sure to be a refreshing treat on a hot summer day and as an added bonus, also have those tasty little gummies in the middle.

5. Step through kelp forests

One of the defining features of an under-the-sea party should be all the kelp and seaweed growing underwater. You can imitate them really easily by using metallic foil fringe curtains! This three-pack of blue foil fringe from Amazon is a great option–they also come in green, so if you’re looking to recreate kelp that’s the way to go!

6. Turn your cupcakes into a school of fish

There are so many great under-the-sea party ideas that really get in touch with your creative side. The theme leaves so much room to play around and turn just about everything into a fun little detail. Look how cute these little fishy cupcakes from Two Sisters are! They leave room for custom cupcake toppers if you’re looking to include those as well.

7. Pose with a mermaid in a photo booth

We all know how much a photo booth can really make a big difference at a party. Allowing everyone to get some fun, themed pictures is a treat for both you and your guests. Order up a pack of fun underwater-themed photo booth props from Amazon to get started.

Then, you’re going to need a venue with a photo booth. That’s where Peerspace comes in handy. The platform offers you access to plenty of awesome venues that come with one ready-to-go. We love this Los Angeles home with a pool, hot tub, and a photo booth! It’s truly the ultimate party pad for any under-the-sea party.

8. Invite guests to your underwater kingdom with themed invitations

Getting everyone on board with your theme before the party is always the right move. Whether you’re sending invites digitally or through the mail, make sure they are clear about what the theme is. We recommend something like these editable under-the-sea birthday invites from Sugar Puff Kids on Etsy. They’re easily customized to your little mermaid’s name and clue your guests in on the type of party you’re having.

9. Have your snacks with themed dishes and cutlery

Did you know that it’s super easy these days to find complete sets of themed cutlery for your parties? No more going to the party store and having to find everything separately. Now, you can go to Amazon and find things like this huge 171 piece under the sea party decorations tableware set!

Love all things sea and sand? Then you need to see our tropical theme party ideas next!

10. Find the pearl in oyster cookies

Part of the allure of the deep ocean is the dream of finding sunken treasure or finding a massive pearl in a clam. Make sure everyone finds a treasure of their own with these easy-to-make oyster cookies from Smart Party Planning. Each one has a white pearl-shaped candy inside so nobody will go home empty-handed – or with an empty stomach!

Not much for baking? That’s okay! Book a bakery on Peerspace that doubles as an event space and see if the host can whip up these oyster and pearl cookies and other under-the-sea treats on your behalf. We love this spacious and modern retail bakery in Chicago, IL for this suggestion!

11. Throw the ultimate pirate battle

There are kids who are obsessed with the ocean because of mermaids, and others who love the pirate life! Want to have a party suitable for your own little pirate lord or lady? Then check out this awesome outdoor pirate village in Morgan Hill, CA! It is nearly 40,000 square feet of pirate ships, treasure chests, and other swashbuckling attractions. Your kid and their friends will flip out when they see it all in person!

12. Dress as your favorite sea creature

Who doesn’t love a costume party? Have each of your guests dress up as their favorite sea creature and give them a chance to explain why to the rest of the party. Or, try something like these sea animal party headbands over at Amazon for some adorable results.

Under the sea party ideas: conclusion

We hope these sweet under-the-sea party ideas have you feeling ready (and excited!) about hosting such an adorably themed party. If you’re planning your party for your child, they will definitely be enchanted by the atmosphere you create and all of the fun activities you have planned!

Remember that you can book a stylish, amenity-packed event venue on Peerspace to make your hosting duties much easier. Reach out to your venue’s host with any questions or requests, and they’ll be happy to help. Between Peerspace’s venue and its amazing hosts, planning your themed party will be a (sea) breeze!

Find unique party venues on Peerspace