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Party Under the Deep Blue Sea

When my 2-year old son took a liking to the Octonauts television show, I was excited to throw him an Octonauts-themed party for his 3rd birthday. Although the images you’ll see below are geared specifically towards that Octonauts theme, they can easily be adapted for any ocean party theme, including mermaids or just simply “Under the Sea.”

If you’re wondering if I crafted that super cool “Gup A” in the featured image above, the answer is YES! It’s a good-sized box covered in light blue duct tape with a working light so my little Octonaut can see his way through the dark waters of the deep blue sea. It took a while to make, but it was totally worth the effort. Just look at that happy little boy!

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Decorations & Activities

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Invitations & Party Favors

DIY Your Own

Party Food

Themed Snacks

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Click on the links below for a list of supplies needed to create the decorations, invitations, and party favors/bags I describe in this post.

Ocean Party Decorations

Blue, green, and light orange cardstock


Large pink balloon

Pink streamers

Black, white and pink paper

Thick copper or brass wire (for monacle)

Colored paper lanterns

Disposable plastic tablecloths (matching)

Streamers (matching)

Paper ribbon (matching)

Streamers in various shades of blue, green, and purple

Red paper plates

Red cardstock

Googly eyes

Tissue paper in pastel colors

Ocean Party Games & Activities

Small plastic ocean animals (I bought 3 bags so there were repeats of the animals)

Camera or smart phone

Bingo cards (use PowerPoint to create different versions of the cards)


Plain paper hats or paper bowls (if you can't find the hats)

Ocean-themed stickers

Ocean Party Favors

White favor boxes

Printer to print copies of the Octonauts band-aid

Blue and white felt

Sewing supplies

Party favors, such as a compass, eye patch, stickers, or small plastic ocean animals

Check Out These Party Decorations!


Ocean Party Decorations

Octonauts Under the Sea Party Decorations

As I mentioned above, many of the decorations you'll find below were designed with the Octonauts TV show in mind. However, with so many options to choose from, you shouldn't have any trouble coming up with variations on that theme that will work for your party.

Explore - Rescue - Protect

This is the Octonauts motto, but it could easily be converted into a “Happy Birthday” banner. Tip: when I construct banners like this, I usually have to either search the internet a bit to find adequately-sized images or draw them myself on my iPad. Smaller image files will appear blurry when printed out to this size. If you'd like to skip the trouble of designing your own banner, visit my Party Shop for printables that make this whole decorating thing a snap!

Image credit: DetailsPartyDesigns

Such a Smart Octopus...

Studies show the octopus is actually pretty intelligent compared to other creatures with similar brain sizes. Although this octopus is modeled after Professor Inkling of the Octonauts, it could be any octopus in the deep blue sea. A large balloon and pink streamers partnered to create our floating octopus. If you want him to look book-smart, add a monocle made from craft wire!

Image credit: DetailsPartyDesigns

Jellyfish (just add Peanut Butter Fish)

These elegant jellyfish are made from colored paper lanterns, streamers, disposable tablecloths, and ribbon. They did take a while to construct, but the effect was very cool, so much so that my kids wanted to keep them up for several weeks after the party.

Image credit: DetailsPartyDesigns

Kelp Forest

Knock, knock.

Who’s there?


Kelp who?

Kelp me, I ran out of time to finish my decorations!

I had fully intended for this kelp forest to extend beyond the one wall, but time didn’t allow for that. If you do something like this for your own party, be sure to allow plenty of time for set-up. Twisting all those streamers just right is a much more lengthy process than one might think!

Image credit: DetailsPartyDesigns

Cute Crabs

I may have lost track of time on this decoration, but I did manage to make a couple adorable paper plate crabs for the ocean floor!

Image credit: DetailsPartyDesigns

Beyond the Coral Reef

My coral patches were made using pastel-colored tissue paper (they’re on the floor on either side of the sliding door). I had hopes of designing a larger reef system…something that would be more permanent…but I had a very limited amount of time to prep for the party so as to surprise my son when he woke up from his nap. There are plenty of design ideas online for coral reef decorations, but I’m thinking a reef made from felt might be more sturdy and stand out better.

Image credit: DetailsPartyDesigns

Cool Party Game Supplies!


Ocean Party Games and Activities

Under the Sea Party Games and Activities

Since this party was for toddlers, the activities were a bit more sparse than usual for me. I went with the "classic" Ocean Bingo and an ocean-themed craft. Downstairs, I filled a play tent with colored plastic balls (the kind you use in ball pits) and the kids took turns "splashing around" in the sea. I have photos from the play tent, but they're really chaotic, so I'll just leave it up to your imagination!

Image credit: Ron Jones

Ocean Bingo

If you’ve read any of my previous posts, you know by now that I don’t do “normal” when it comes to games or activities for my parties. As this was a party for a 3-year old, I knew I couldn’t get too complicated. So, I decided on Bingo…ocean-style!

Rather than just having everyone sit around marking off their bingo cards as I called out random letters and numbers (which wouldn’t work that great for the younger kids anyway), I decided to create a bingo game in which the kids had to find their markers. I bought a bunch of small, plastic ocean critters from a local party supply store, photographed them, and then created bingo cards with the ocean critter photos in place of the numbers. Then I hid all of the critters around the house, handed out a bingo card to each kid, and set them loose. The first kid to find 5 critters in a line (that matched the photos on their card) was the winner!

One bit of advice: if you have a mix of older and younger kids at your party, make some of the critters easier to find than others and ask the older kids to leave the easy finds for the little ones.  

You Can't Go Wrong with Stickers!

My kiddos love stickers - so I gave them various props, (like the white paper bowl on my daughter's head), a considerable pile of ocean stickers and colorful markers, and they were off to the races! We usually do some sort of craft project while waiting for all the party guests to arrive, and this worked out perfectly, especially for the little ones.

Image credit: Ron Jones

Must-Have's for the Snack Table!


Ocean Party Food

Snacks Under the Sea

I was thrilled with how many cute food names I found related to the Octonauts. I had a lot of fun putting together this spread, and the kids had even more fun eating it all!

Sea Snacks

I found lots of great ideas for ocean-themed snacks for our party, including goldfish (easy), kelp cakes (corn muffins), shark teeth (mozzarella cheese), and kelp kabobs (green grapes on skewers). Add a little jellyfish juice and some cute, fishy cupcakes, and our sea snack table was complete!

Image credit: Ron Jones

Image credit: Ron Jones

Fishy Cupcakes and Octopus Hummus

Normally I would call upon our trusty neighborhood grocery store bakery to create an awesome ocean-themed cake, but I couldn't resist making these adorable fishy cupcakes myself! 

If you've ever seen the Octonauts show, you may recall the impossible-to-pronounce Humuhumunukunukuaua'a, which is a reef triggerfish and one of the species the Octonauts protect. Try teaching that word to a group of toddlers (and their parents)!

Image credit: Ron Jones

Scooping Up Some Goldfish!

He really loved using the fish net to "capture" goldfish. Funny thing is, he ate that entire net-ful without even blinking an eye!

Image credit: Ron Jones

Party Favor Bags & Goodies!


Ocean Party Invitations and Favors

One-of-a-Kind Octonauts Party Invitations and DIY Favor Bags

Check out these adorable Octonauts party invitations and favors! I really love this theme because there are so many fun, ocean-y ideas for party favors.

Octonauts Pals Invitation

Although parts of this card appear to be three dimensional, that's an illusion. The only thing that's "3D" is the light hanging from the top of the Gup. You can find this cute printable with 3 of the Octonauts pals exploring the ocean in their favorite Gup in my Party Shop.

Image credit: DetailsPartyDesigns

Octonauts Characters Invitation

This is actually a birthday card, but could easily be converted into a cute, scrapbook style invitation.

Image credit: inkantations-and-inkarnations.blogspot.com

Gup Invitation

This double-sided invitation incorporates several components of the Octonauts theme: the trusty Gup, Captain Barnacles, and the Octonauts logo. If you zoom in on the text, you'll see the invite itself is true to the theme as well.

Image credit: @SharonsPaperStu (Pinterest)

Octonauts Party Favor "Bags"

This is actually the idea I used for my son's party, but for some reason I didn't get a photo of my version. Check out her website for a description of each item in the box - very thematic!  

Image credit: DirectorJewels.com

Octonauts Hat

You can make these cute hats out of felt or paper. Such a fun idea and memorable party favor!  

Image credit: BoyMamaTeacherMama.com

Octonauts Character Favor Bags

If you prefer the traditional favor bag style, here's another Octonauts example. I imagine it wouldn't be hard to design a Captain Barnacles version as well! 

Image credit: Etsy.com

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