Under The Sea Fancy Dress: Outfits For Ocean And Beach Parties

Under the sea is the easiest theme to look good at and the easiest to phone in. Blue clothes and a shell necklace is not a costume.

The outfits that work are either properly beautiful or properly silly. The middle ground is where the disappointing ones live.

Here's both ends, plus the group options and how to dress the room.

Honest note: we make cards, pin badges, prints and party decorations, not costumes.

The beautiful end

• Mermaid: a fishtail skirt, shell top, wet-look hair and iridescent make-up.
• Sea witch: black and purple, dramatic eyeliner, tentacle sleeves cut from fabric.
• Siren or sea goddess: floaty blue-green layers, pearls, a driftwood crown.
• Coral reef: layered orange, pink and yellow tulle with pipe-cleaner branches.
• Jellyfish: a clear umbrella with ribbons hanging from it and fairy lights inside. It's the best-looking cheap costume there is.

The funny end

• SpongeBob - the most literal answer to 'under the sea' there is, and a full-body suit gets a reaction from every single person at the party.
• Patrick Star alongside it if you're going as a pair - Read the guide
• An inflatable shark, a lobster, or a crab with cardboard claws.
• A deep sea diver in a cardboard helmet with a torch inside it.
• Seaweed: green fabric strips on a green base, which takes twenty minutes.
• A bath, made from a cardboard box with a shower cap and a rubber duck.

Group and family themes

• The Little Mermaid cast: Ariel, Ursula, Sebastian, Flounder, Triton.
• Finding Nemo: Nemo, Dory, Marlin, Crush and the seagulls in matching 'Mine' t-shirts.
• A whole reef: one coral, one jellyfish, one clownfish, one turtle.
• Pirates versus sea creatures, which lets everyone pick an effort level.
• SpongeBob's Bikini Bottom: SpongeBob, Patrick, Squidward, Mr Krabs and Sandy.

DIY builds in under an hour

• Jellyfish: clear umbrella, ribbons, battery fairy lights.
• Octopus: grey hoodie with six stuffed tights sewn to the back.
• Fish: a cardboard tail and fins stapled to a plain t-shirt, painted in two colours.
• Shark: grey hoodie, white felt teeth round the hood opening, a grey cardboard fin.
• Bubbles: clear balloons safety-pinned all over a plain outfit.
• Full budget guide - Read the guide

Dressing the room

• Blue and green balloons at floor level rather than ceiling level - it reads as water
• Blue and turquoise bunting across the ceiling - Shop the range
• Tissue paper seaweed taped to the walls and left to hang loose.
• Table confetti in blues and silvers - Shop the range Shop this card
• Party planning by theme - Read the guide

Shop party decorations

How to write it so it lands

• Beautiful or silly - the middle ground disappoints.
• A clear umbrella jellyfish beats most bought costumes.
• SpongeBob is the funniest literal answer to the brief.
• Balloons low, not high, so the room reads as water.

Where to shop next

• Party supplies
• Bunting and banners
• Funny pin badges
• Funny cards
• Table confetti
• How to plan a themed party
• 2000s fancy dress ideas
• Duo fancy dress ideas
• Pub crawl fancy dress themes
• Cartoon character fancy dress
• Funny fancy dress ideas
• Fancy dress ideas
• Fancy dress party themes
• How to throw a fancy dress party
• Last minute fancy dress ideas
• DIY fancy dress on a budget
• Fancy dress prize ideas
• 80s and 90s party ideas
• Planning the party? Birthday party ideas
• How to make a balloon arch
• Photo booth prop ideas
• Pin badges
• All guides

Frequently asked questions

What can I wear to an under the sea party?

Go beautiful or go silly. Mermaid, sea witch, jellyfish and coral reef at one end; SpongeBob, a lobster, an inflatable shark or a cardboard deep sea diver at the other. Blue clothes and a shell necklace is not a costume.

What is the best cheap under the sea costume?

A jellyfish made from a clear umbrella with ribbons hanging off it and battery fairy lights inside. It costs very little and looks better than most bought costumes.

What are good group under the sea costumes?

The Little Mermaid cast, Finding Nemo, a whole reef with one coral, one jellyfish and one clownfish, or Bikini Bottom with SpongeBob, Patrick, Squidward and Mr Krabs.

How do you decorate for an under the sea party?

Blue and green balloons at floor level rather than up high so it reads as water, bunting across the ceiling, tissue paper seaweed hanging loose on the walls and blue and silver confetti on the tables.

Do you sell fancy dress costumes?

No. We design and print greetings cards, enamel pin badges, prints and party decorations in the UK. Costumes are recommendations from elsewhere - the only things linked to our own shop are ours.