Dive Into Magic: Under the Sea (Oneder the Sea) Birthday Party Theme Ideas!

When our daughter, Lyla, turned one I decided to use an Under the Sea (“Oneder the Sea”) birthday party theme.

Although we used this theme for our little one’s first birthday party this theme could be an Under the Sea party for any age!

There are so many things you can do with decor and food to bring this theme together in a fun, whimsical, and magical way.

A decorated table with food. This post is about ideas for a Oneder the Sea Birthday Party,Pin

Under the Sea/Oneder the Sea Theme First Birthday Party Ideas

Let’s dive into the ocean of ideas that will make your baby’s milestone birthday an unforgettable adventure under the sea! Haha!

Enjoy this inspo for a delightful Under the Sea or “Oneder” the Sea themed birthday party! I hope it inspires a lot of ideas!

Invitations

We sent e-vites for this party. You can see the ones we sent here: Evites for Oneder the Sea birthday theme.

Party Decor:

We went with slightly feminine colors for our daughter’s birthday but this is definitely a gender neutral theme that would work with almost any colors!

(Some of the links below are affiliate links. This means that I might make a small commission if you purchase through my link but there is never any additional charge to you.)

A balloon arch in peaches, greens, pinks, and purples. Pin

BALLOONS: I almost always have balloons as part of the decor for my parties not only because I love them but also because my sister-in-law has a side business making balloon arches. She always helps me bring my visions to life!

We cut out and painted the arches that you see in the photo below from large foam boards and then put together the balloons.

I get my balloons from Amazon. I like to pick out a variety of colors and mix and match the colors and different sizes.

However, you can also pick balloons in all different colors that are already packaged together specifically for balloon arches. I think this package in bright shades of blue and green would be perfect for a Oneder the Sea themed party.

It is also fun to add some shell shaped or fish tail shaped balloons to your arch!

If you are going to be blowing up a bunch of balloons then you MUST have a balloon pump. It’s truly a life saver!

A ballon arch topped with a fish tail balloon. Pin

FRONT ENTRANCE: At the front door I asked people to write a note to Lyla that would be given to her when she was 18! That was so fun and I have them put away for her and can’t wait to see them again.

Oneder the Sea birthday party ideas. Pin

PHOTO BOARD: We also did a photo board of Lyla’s first year! I covered it with more of the netting and used little clothespins to pin on the photos.

A photo board with photos from a child's first year. The board is covered with fishing type net and seems to be set up for a birthday party. Pin

SIGN: We placed a sign next to the photo board that told all the ways that Lyla had grown in her first year.

A board with everything about a babies first year. Pin

TABLE DECOR: My favorite part of the decor for any party is the table decor!

I turned my dining table sideways against the window to allow more space in the middle of the room and kept it really simple by using pretty gauze runners in the colors of the balloons.

My runners came from Amazon and I actually purchased them a couple of years ago to use for my sister’s engagement party.

I loved them so much that I have been collecting various colors ever since. They come in handy for so many events.

A decorated table in front of a window. There is food on the table. Below the table are balloons. And hanging above the table are lantern style jelly fish. This is for a Oneder the Sea themed birthday party. Pin

HANGING DECOR: Above the table I hung pink lantern jellyfish from the ceiling. They looked so cute fluttering above the table!

If you aren’t wanting to use pink these also come in shades of blue and green!

lantern style jellyfish in pink hanging above a table. Pin

DRINK AND DESSERT STATION: I put the drinks and desserts on the bar of my kitchen.

That area was decorated with fish type netting and more scattered seashells. I also used this large shell that we stuffed with even more balloons! I bought mine from Amazon and unfortunately can’t find it anymore but here is a fish tail that would be fun as well as an adorable number one!

I also scattered some real shells on the table and on the kitchen island that I have collected over the years from multiple visits to Florida.

Large shell cutout stuffed with different shades of blue balloons on a kitchen island. Pin

PLATES AND NAPKINS: We used simple but pretty paper plates for the main course and some shell shaped plates for dessert.

Scalloped paper party plates. Pin

I also used these cute “shellabration” napkins. Mine came from Dollar Tree but here are some other cute napkins from Amazon.

Napkins that say Let's Shellebrate. This are part of the decor for a Oneder the Sea Birthday Party.Pin

I used these pink and green hobnail glasses with the straws for the adults. I had originally purchased these for another event that I hosted but have used them again and again.

I used paper straws for the adult beverages but look how cute these ocean themed straws would be if you were serving children’s drinks with a straw!

Pink and green hobnail glasses set up for a party. Pin

For the kids I found these cute little plastic shell cups with straws at Dollar Tree. I was hoping that this would help with spills! Here are some cute ones from Amazon.

Shell shaped plastic cups. Pin

Some cute little shell string lights added some interest in this area.

I served pineapple punch from a shell shaped punch bowl.

Shell shaped punch bowl. Pin

OTHER ONEDER THE SEA DECOR: I found some more decor ideas that I think would work great for this theme!

Under the Sea / Oneder the Sea Party Food:

It was so much fun setting up the food for this party! We honestly kept it very simple but it was delicious.

For the main course I made these adorable chicken salad croissant sandwiches. A toothpick and some googly eyes made them look like little crabs.

Closeup of croissant sandwiches with chicken salad. There are toothpicks with google eyes on top that make the sandwiches look like little crabs. Pin

We also had a huge charcuterie board with bread, meats, nuts, cheeses, veggies, sauces, and dips as well as a watermelon fruit bowl.

Gorgeous charcuterie board shot from above. Pin

SERVING PIECES THAT I OFTEN USE FOR PARTIES:

  • One of my favorite party dishes is the tiered tray that you can see in some of the photos above. I use it almost every time we have guests and I love it. Highly recommend.
  • We also use a wooden serving tray with a small lip that you can see in the photo of the croissant sandwiches all the time. I used it for serving at this party but it is great to for charcuteries boards as well.
  • In my opinion you can never have too many white serving bowls both for everyday use and for parties. I had several on our food table with things like chips and goldfish. This tiered stand with bowls would be really great for serving!
  • I love using apothecary type jars for parties. When they are filled they make everything look so pretty. You can see that I had them above filled with Swedish fish, sea blue rock candy, and other little treats.
Cut out of a shell sitting on a kitchen island filled with balloons. Pin

I did have a smash cake just for fun for Lyla but other than that we didn’t have cake at this party.

Parent with a child eating their birthday cake at a Oneder the Sea Birthday Party themePin

For the main dessert we had a local ice cream truck come by! That was so much fun and it encouraged guests to hang out on the front porch rather than everyone being inside the house.

Photo of an ice cream food truck. Pin
Mom and daughter eating ice cream. Pin

Because I am always extra I also had a local bakery make some of the cutest macarons I have ever seen. Not only were adorable, they were also delicious!

Adorable crab macarons.Pin

Party Favors and Games:

For a party favor we decided to do something really practical and let all the kids take home a beach towel. I think the parent appreciated not having to deal with bags of candy and toys!

I found them in a pack of 6 in different colors!

Ideas for a party favor for an Oneder the Sea birthday party is beach towels. Pin

I hope that this will help you come up with your own Onder the Sea birthday party ideas!

Thanks so much for stopping by!

Thanks for sharing!

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