Shark and Mermaid Costumes for Kids and Adults: Which Sea Look, and What to Add

The best shark costume depends on who is wearing it: a plush shark tunic slips over everyday clothes for school-age children, and an inflatable shark is the big, eye-catching option for kids. Kids lead here, because about three in four of the shark and mermaid costumes sold on our UK site in the 12 months to 31 October 2026 were kids' sizes. Mermaids are the other half of the pairing, from a metallic dress for grown-ups to a pirate-carrying-mermaid inflatable for kids.

We keep this guide in the water. Our guide to animal costumes for kids and adults covers the rest of the zoo, our shark piggyback included.

Shark or mermaid: which sea look suits whom?

The shark suits anyone after a laugh or a mild scare over everyday clothes; the mermaid suits anyone after sparkle and photos. They pair, too: the shark chases, the mermaid gets carried off. Our five costumes and three add-ons split across the two looks like this (product pages, 4 November 2026):

Which shark costume is easiest for kids to wear?

A plush shark tunic is the easiest shark costume for kids to wear: it pulls over their own clothes and needs no batteries, so arms and legs stay free to run. There are around 500 species of shark, according to the Natural History Museum; our two tunics, the great white and the hammerhead, are made for school-age children, not under-3s.

Kids Great White Shark Tunic Costume: the classic sea predator

The Kids Great White Shark Tunic Costume is a sea-blue and grey plush tabard, its shark head finished with realistic eyes and teeth and a tail at the back. It is 100% polyester, meets UK and EU toy safety standards, and is sized for school-age children; check the size guide on the page before you order. For an outdoor party, put a plain grey long-sleeved top and leggings underneath. Grown-up joining in? Our Shark Fin Headband for Adults needs no costume to change into.

Kids Hammerhead Shark Tunic Costume: the shark with the strange head

The Kids Hammerhead Shark Tunic Costume is grey plush with a white belly and a wide hammer-shaped head with a big eye at each end. Like the great white, it is a 100% polyester tabard with a tail, sized for school-age children. Real hammerheads carry their eyes that way for a reason: the Shark Trust says the position of their eyes lets them see 360 degrees. Want the grown-up to be the bigger shark? Our Adult Shark Bite Hat looks like a shark biting down on your head, with 1.5-inch teeth across the forehead and a tail that hangs 10 to 11 inches down the back.

Are inflatable shark costumes worth it?

An inflatable shark costume is worth it if your child wants to be spotted across the room. About a third of the shark costume searches that show our UK site in Google ask for an inflatable or blow-up shark (10 August to 1 November 2026). Two practical points: the fan needs 4 x AA batteries, sold separately, so fit and test them the week before, and a T-shirt and leggings underneath are plenty. Our guide to wearing an inflatable costume covers fitting the batteries through to sitting down; our kids inflatable costumes show the wider range, and our inflatable costumes ranked and kids inflatable alien costumes guides have more blow-up ideas.

Kids Inflatable Big Mouth Shark Costume: a face in the jaws

The Kids Inflatable Big Mouth Shark Costume puts the wearer's face inside the shark's open mouth, ringed with white teeth and a red drip print below the jaw, which gives it a Halloween edge. Over 4 hours of air comes from a built-in fan on 4 x AA batteries, sold separately; elasticated seals help hold it in, and there is a built-in pocket. It is one size for most children, with the size chart in the product images.

Which mermaid costume works for adults and kids?

For adults, a mermaid dress does the work on its own; for kids, an inflatable mermaid turns the costume into a joke as well as a look. Our two picks: a metallic dress in five sizes and a pick-me-up inflatable in three.

Adult Oceanic Mermaid Costume: shimmer in five sizes

The Adult Oceanic Mermaid Costume is a shimmering pink and blue dress in high-shine metallic stretch fabric, with a matching headband in the pack. It runs in five UK dress sizes, Small (4-6) to X-Large (20-22); between sizes, we suggest sizing up. Every costume goes through over 30 measurement checks. The skirt falls to the floor in layered tulle, so try it on with the shoes you will wear. Our Long Mermaid Wig, long, wavy and blue in one adult size, finishes it.

Kids Pirate Mermaid Pick Me Up Inflatable Costume: caught by a pirate

The Kids Pirate Mermaid Pick Me Up Inflatable Costume is an illusion: your child plays the mermaid, scaled teal tail and all, and an inflatable bearded pirate appears to carry them off. Its fan and battery pack takes 4 x AA batteries, sold separately, and runs for over 4 hours; hook-and-loop fastening means it goes on and comes off fast. Sizes are small, medium and large. Siblings who want to do the carrying can find a full crew in our guide to kids pirate costumes.

What can you add to finish a shark or mermaid look?

A long blue wig finishes a mermaid; a fin headband or a shark bite hat finishes a shark. Each of our three add-ons fills a different gap:

• Long Mermaid Wig: long, wavy and blue, one size for most adults. It finishes the Oceanic dress, or turns a plain blue outfit into a mermaid.
• Shark Fin Headband for Adults: a 5.5-inch grey fin on a fabric-wrapped band, for ages 14 and over, sold singly or in packs of 2, 4, 6 or 12.
• Adult Shark Bite Hat: about 20 inches from nose to tail, for heads of about 55 to 60 cm, ages 14 and up. The shark look for a grown-up staying in their own clothes; for a full blow-up suit, browse our adult inflatable costumes.

From home: shells or a starfish clip for a mermaid, and grey or navy layers under a shark tunic to carry its colours down to the shoes.

How do you dress a family or group under the sea?

Dress a family or group by mixing the two looks: sharks and mermaids side by side read as one theme, so nobody has to match. Four casts from this range:

• Siblings: the great white and the hammerhead tunics, one each, so the photo shows two different sharks.
• Parent and child: a kids Big Mouth Shark with a grown-up in the Shark Bite Hat, or a mermaid parent in the Oceanic dress with a child in the pirate-mermaid inflatable.
• Teams and clubs: a 12-pack of shark fin headbands, for ages 14 and over, dresses the parents and older swimmers cheering from the spectator seats at a swimming gala.
• World Book Day: Thursday 4 March 2027 is the date, according to World Book Day. Pick a sea story and send a shark or a mermaid; classmates can choose from our kids World Book Day costumes.

A shark costume is less exotic than it looks: at least 21 species of shark live in British waters all year round, according to the Shark Trust. To fill out the cast with other animals, browse our kids animal costumes.

How do you size and wash shark and mermaid costumes?

Size the kids tunics and inflatables by the size guide on each product page and the adult dress by your usual UK dress size, then wash the fabric ones by hand and wipe the inflatables:

Fabric costumes take a cold hand wash and an air dry; inflatables take a sponge wipe with the fan pack removed. Nothing here goes in the washing machine. All of our kids' products are safety tested by accredited labs.

Whoever you buy from, the Office for Product Safety and Standards advises buying children's costumes from trusted sources and taking care near fires, particularly open flames. Its 2024 check of 128 costumes for under-7s from online marketplaces found more than 80 per cent failed basic safety tests, most of them on labelling.

Frequently asked questions