Mermaid Birthday Party Ideas: How My Friend and I Threw a Backyard Under-the-Sea Party for 11 Six-Year-Olds ($79 Total)

Vanessa called me on a Wednesday night, half-panicking. “Chloe wants a mermaid party. I looked up mermaid performers and they start at $275. For one hour. In a costume that honestly looked like it came from Spirit Halloween.”

I told her to close the browser tab.

Look—I’ve thrown enough kids’ parties at this point to know that the theme isn’t about hiring a character. It’s about the world you build. And mermaid is one of those themes where a few cheap tricks do 90% of the work. Blue tablecloths. Fishnet. A bubble machine running in the corner. That’s it. That’s the ocean.

Chloe was turning 6, and Vanessa wanted the party in her backyard in Mason, just north of Cincinnati. We had 11 kids coming. And we did the whole thing for $79.

Here’s exactly what we set up, what flopped, and the one decoration trick that made three parents ask where we hired a decorator. (We didn’t.)

The Decoration Trick That Made Everything Work

I bought a decorative fishnet from Amazon. $7.99 for a big one. We draped it across the fence behind the food table and stuck dollar store plastic shells, starfish, and little fish in the holes.

That was the entire “wow” moment. Every parent who walked in said something about it. One dad literally asked if we’d hired someone.

The rest of the decorations were embarrassingly simple: four blue plastic tablecloths ($1 each at Dollar Tree) on every surface. Two green and two blue crepe streamers twisted together and hung from the fence posts—instant seaweed. A $14 bubble machine from Target running on the patio the entire time.

Total decoration cost: $29.96. And honestly, the bubble machine did more than everything else combined. There’s something about bubbles drifting through a backyard that just makes it feel underwater. Two girls stood near it for probably eight minutes just watching bubbles land on their arms.

The Arrival Activity: Shell Necklace Station

Kids don’t all show up at the same time. You need something at the door that doesn’t require supervision. I’ve done hat decorating for this in other parties and it works great—but for mermaid, I wanted something that felt more on-theme.

Shell necklaces. But not real shells, because real shells are expensive and weirdly sharp.

The night before, Vanessa and I dyed penne pasta with food coloring and vinegar. Three batches: purple, teal, and pink. Spread them on wax paper to dry overnight. Total cost for the pasta, food coloring, and string: $4.83.

Each kid got a paper plate with a pile of dyed pasta and a piece of cotton string with a piece of tape wrapped around one end (the “needle”). They strung necklaces while waiting for everyone to arrive. The whole station ran itself for 20 minutes. Owen—my five-year-old—made four necklaces and wore all of them simultaneously.

Mermaid Crown Decorating

This was the main craft station once everyone arrived. I brought two packs of pastel cone hats with pom poms and set them out with stick-on jewel sheets ($3.49 from Michaels), iridescent star stickers, and some leftover ribbons from my Etsy supply closet.

The cone shape plus the pastel colors already look like mermaid crowns without doing anything to them. The pom pom on top reads as a pearl or a sea anemone depending on which six-year-old you ask. Once kids stuck jewels all over them, they genuinely looked like something from a craft tutorial video.

Twelve minutes. That’s how long the decorating took. Faster than most parties I’ve done—I think because sticker jewels are quicker than markers or paint. Every kid wore their crown the rest of the party. Chloe slept in hers that night, which Vanessa sent me a photo of at 10 PM with the caption “she won’t take it off.”

Mermaid Tail Relay Race

This was Vanessa’s idea and honestly it was the highlight of the whole party.

We took old pillowcases—she had a stack from a linen closet purge—and the kids stepped into them up to their waist. That’s their mermaid tail. Then they had to hop from the start line to a lawn chair and back.

It was chaos. Beautiful, hilarious chaos.

Three kids fell on the first try. Nobody cried—they just laughed and got back up. One boy, Marcus (yes, same Marcus from the pool party—he shows up everywhere), figured out that if you hold the pillowcase edges and shuffle instead of hop, you go faster. Within two rounds every kid was doing the Marcus shuffle.

We ran five rounds. Took about 15 minutes. Cost: $0, assuming you own pillowcases. If you don’t, thrift store pillowcases are like 50 cents each.

Treasure Dive

This was the activity I was most excited about and also the one that caused the biggest mistake of the day.

I filled Vanessa’s two kiddie pools with water and dumped in a bag of acrylic gems ($6.99 for 200 on Amazon), some pennies, and a handful of plastic gold coins left over from Owen’s pirate party. Kids had to reach in and grab as many treasures as they could in 30 seconds.

Here’s where I messed up. I added blue food coloring to the water so it would look like the ocean.

It did look like the ocean. Gorgeous, deep blue ocean water. And then 11 kids stuck their hands and arms in it, and for the next two days, every kid at that party had blue-tinted hands. I got exactly one text from a parent about it. (She thought it was funny. I was relieved.)

If I did this again, I’d skip the food coloring entirely. Clear water with gems at the bottom is plenty magical. You don’t need blue hands on school picture day.

Giant Bubble Station

I brought two giant bubble wands I’d made from dowel rods and cotton string. Recipe is all over YouTube—costs maybe $2 in materials. Mixed up bubble solution in a plastic bin: water, dish soap, a tablespoon of glycerin.

This station ran for the entire party. No supervision needed after the first demo. Kids would wander over, dip, wave, watch the bubble float across the yard, and wander back to whatever else was happening.

Giant bubbles are underrated as a party activity. They cost almost nothing. They work for ages 3 to 43 (Vanessa’s husband Dave was out there making bubbles for a solid ten minutes while pretending to “test” them). And they photograph beautifully—the mermaid crown plus a giant rainbow bubble in the background was the shot that Vanessa posted on Facebook. 847 likes.

Food: Rename Everything

This strategy works for literally every party theme and I will never stop doing it.

We served:

• Mermaid Scales — goldfish crackers in bowls
• Ocean Water — blue Jello cups (box of Jello + plastic cups = $3.20 for 14 cups)
• Seaweed Strips — green apple slices. One kid wrinkled her nose and said “that’s not seaweed.” Chloe said “it’s MERMAID seaweed” and that settled it
• Pirate Gold — Ritz crackers with peanut butter (allergy-checked with all parents first)
• Sand Dollars — plain sugar cookies from the bakery section at Kroger, $3.99/dozen

Cake was homemade by Vanessa—blue buttercream with Swedish Fish stuck on top and graham cracker crumbs around the base for “sand.” Not Pinterest-perfect. Better. It looked like a kid’s idea of an ocean, which is exactly right for a kid’s party.

Three Things I’d Do Differently

1. No food coloring in water. Already covered this. Blue hands. Two days. Learn from me.

2. Get a plug-in bubble machine, not battery. Our battery-powered one ate through four AA batteries in 90 minutes. I had to run inside for more. A plug-in version with an extension cord would’ve been $3 more and zero hassle.

3. The fishnet was too fine. The decorative fishnet I bought had small holes—about 1 inch. Two kids stuck their fingers through and got briefly tangled. Nobody got hurt, but I had a small cardiac event. For the next party I’d get the wide-hole fishnet (the $6 one with 3-4 inch holes). Same visual effect. Zero tangling risk. Actually, if I were to add more hats to the decor, I might try DIY assembly hat kits as another craft station—they’d double as party favors so you skip separate favor bags entirely.

The Budget

Total for 11 kids: $79.14

Breakdown:

• Fishnet + plastic sea creatures: $11.47
• Blue tablecloths x4: $4.00
• Bubble machine: $14.00
• Crepe streamers: $2.49
• Pastel cone hats: $13.98 (we only opened one pack, returned the other)
• Stick-on jewels + stickers: $5.48
• Pasta + food coloring + string: $4.83
• Acrylic gems: $6.99
• Giant bubble supplies: $2.40
• Food (Jello, crackers, fruit, cookies, candy): $13.50

That’s $7.19 per kid. The local pool party venue wanted $189 for two hours plus you bring your own food. So.

FAQ

Can boys come to a mermaid birthday party?

Yes. Four of Chloe’s 11 guests were boys. Marcus dominated the relay race and collected more gems in the treasure dive than anyone. Mermen exist. Nobody questioned it. I covered this same topic when we did a garden party with mixed genders—kids genuinely don’t care about theme gender unless adults make it weird.

What’s the best age for a mermaid party?

4 through 7 is the sweet spot. Younger than 4 and they don’t really get the theme. Older than 8 and they start wanting something less “little kid.” Chloe at 6 was peak mermaid obsession—she had mermaid sheets, a mermaid backpack, and had watched Moana approximately 400 times (close enough).

Can you do a mermaid party indoors?

Absolutely. Skip the kiddie pool treasure dive (or use a dry version with gems hidden in a bin of blue rice). The bubble machine works indoors if you put a towel under it. Shell necklace station and crown decorating work anywhere. Relay race works in a long hallway or basement. We did ours outside because it was early June in Ohio and 74 degrees, but the whole thing would transfer to a living room without much adjustment.

How long should a mermaid birthday party last?

Two hours is right. We ran from 2:00 to 4:00 PM. The schedule was: necklace station during arrival (2:00-2:20), crown decorating (2:20-2:35), relay race (2:35-2:50), treasure dive (2:50-3:10), free play + bubbles (3:10-3:30), cake and presents (3:30-4:00). We finished right on time with no dead spots.

What do you put in mermaid party favor bags?

We didn’t do favor bags. Every kid went home wearing a decorated mermaid crown and a pasta shell necklace. That’s two things they made themselves, which kids value more than a plastic bag of candy from Party City. Total favor cost: $0 extra beyond the activity supplies we already bought.

Chloe told Vanessa it was the best birthday she’d ever had. Vanessa told me the fishnet is still on the fence three weeks later because “it actually looks kind of cool.” Dave has not confirmed this opinion.

If your kid is in a mermaid phase—and if they’re between 4 and 7, there’s about a 60% chance they are—just lean into it. Blue tablecloths, fishnet, bubbles. You don’t need a performer in a tail. You need a backyard and $79.