Sharkboy and Lavagirl are a gift for anyone who likes making costumes, because the whole pairing runs on contrast: his cool silver-grey suit with fins and a toothy chest, her hot pink with lava running through it. Get those two colour stories right and people know who you are before they spot a single detail. I build both from stretch basics and add the character on top with felt, craft foam or EVA foam, depending on how much time I have. Below you'll find thirty versions, from a felt build and a closet scramble to foam armour, with adaptations for kids, couples, groups, plus sizes, pregnancy and cold or hot weather.
Building a Dorsal Fin That Won't Flop
Almost every Sharkboy idea below needs a back fin, and it's the piece that goes wrong most often. A fin cut from a single layer of felt droops by the end of the evening, and one cut from thick cardboard is heavy enough to drag the shirt backward at the collar. This is the method I use for a fin that stands up and stays light:
- Draw the fin on paper first and hold it against the wearer's back. For a child, keep it no taller than their hand; for an adult, around the length from wrist to fingertips.
- Cut two fin shapes from grey felt or fleece, plus a slightly smaller insert from craft foam or a plastic folder for stiffness.
- Sandwich the insert between the fabric layers and stitch around the edge, leaving the base open.
- Add a tab of fabric at the base and stitch or Velcro it to a vest or backpack-style harness rather than to a stretchy shirt.
- Angle the fin slightly backward. Straight-up fins catch on car roofs and doorways.
For toddlers, skip the stiffener and stuff the fin lightly with polyester fibre instead, so it squashes flat in a car seat and springs back afterward.
1. Classic Sharkboy And Lavagirl Couple Costume
This is the version I'd make first, because it copies the film's palette most closely. Sharkboy gets a fitted black base layer under a metallic grey foam vest with white teeth, side gills and a light back fin, plus grey pants, fin-shaped arm cuffs, black gloves, silver boot covers and tousled brown hair. Lavagirl's pink jumpsuit carries darker pink armour panels and orange lava lines, with a wavy pink wig, pink arm guards and matching boots. Keep the armour slim on both. A chunky foam vest looks great standing still, but it catches on every doorway and chair back once you start moving.
2. DIY Felt Sharkboy And Lavagirl Costume
Felt is my go-to when someone wants a homemade pair without real sewing skills. For Sharkboy, layer a grey felt chest panel over a black long-sleeve shirt and pants, then add white felt teeth, black outlines, side gills and a cardboard fin covered in silver fabric, with grey felt cuffs and boot covers. Lavagirl starts from a pink sweatsuit with darker pink felt shapes and wavy orange strips glued across the top and pants. Fabric glue holds felt well on cotton sweatshirt fabric, but it peels from slick polyester, so check the label on your base. If you want to wear the clothes again afterward, safety-pin the shapes on instead.
3. Last-Minute Sharkboy And Lavagirl Costume
You can pull this pair together on Halloween afternoon from what's in the closet. Sharkboy wears a charcoal athletic shirt, black joggers, grey sneakers and fingerless gloves, with a shark mouth and small dorsal fin cut from grey poster board and stuck on with fashion tape. Poster board bends and creases after an hour of wear, so I'd keep the fin short. Spike his hair with temporary gel. Lavagirl wears pink leggings, a pink long-sleeve top and pink shoes, with lava lines in orange removable tape, a bright pink bob wig, pink shadow and a light orange foam ball for her lava power. It's rough, but the colours do the work.
4. Kids Sharkboy And Lavagirl Costume
Kids need to sit, run and grab candy, so soft beats accurate. I dress a child Sharkboy in a grey jumpsuit or sweatshirt and joggers, then add a padded fabric vest with felt teeth, bendy side fins and a small foam back fin that won't smack other trick-or-treaters. Grey gloves, silver sneakers and messy hair finish him. A child Lavagirl wears a stretchy pink tracksuit with orange and darker pink fabric strips sewn on, plus pink sneakers, soft arm cuffs and a little face shimmer. Choose a child-sized wig with a comfy cap, or use temporary pink hair colour with an adult helping. Skip masks and big props entirely; clear eyes and free hands matter more than detail on a dark street.
5. Toddler Sharkboy And Lavagirl Sibling Costume
Toddlers will pull at anything stiff, so this sibling pair is all plush. For a little Sharkboy, sew a felt shark-mouth panel onto a grey hooded romper, then stitch a stuffed dorsal fin to the back and two tiny fins to the sleeves. Soft felt teeth around the hood edge replace a headpiece they'd yank off in minutes. Lavagirl's bright pink romper gets orange felt swirls and padded darker pink panels, with a soft pink yarn wig headband and slip-on shoes. Makeup is optional. I'd leave out handheld accessories too, so both kids can hold a grown-up's hand and still be in the family photo.
6. Adult Sharkboy And Lavagirl Couple Costume
For grown-ups, I sharpen the fit rather than add more pieces. Sharkboy wears a sculpted metallic vest over a charcoal compression shirt and slim black utility pants, with moulded arm guards, a bendy dorsal fin, fingerless gloves, silver combat boots and textured brown hair. Lavagirl suits a fitted pink catsuit, or a top and leggings, with flame-shaped magenta panels, a long pink wig, pink ankle boots and matching gauntlets. A body-safe shimmer along the cheekbones looks better on adults than full face paint and won't rub off on everyone you hug. Keep the armour light enough to sit down in, because adult parties involve a lot of sitting.
7. Best-Friend Sharkboy And Lavagirl Costume
These two don't have to be a couple; best friends wear them just as well. One friend takes Sharkboy in a silver-grey athletic jumpsuit, shark-mouth vest, foam fin, arm guards, black gloves and grey boots, with messy hair and cool-toned shading on the face. The other is Lavagirl in a bright pink jumpsuit with orange lava patterns, a layered pink wig, magenta cuffs, pink sneakers, coral shadow and an iridescent shimmer. The detail that matters most for a pair is matching effort. If one of you has carved foam armour and the other has tape on a T-shirt, it looks like two separate costumes, so agree on the material before anyone starts cutting.
8. Gender-Swapped Sharkboy And Lavagirl Costume
Swapping the characters works because the colours and fins carry them, not the body underneath. A feminine Sharkboy could wear a charcoal fitted top, a metallic grey skater skirt over leggings, silver chest armour, shark-fin cuffs and ankle boots, with tousled hair, cool grey eye makeup and a bendy back fin. A masculine Lavagirl suits a hot-pink athletic jumpsuit with magenta panels, orange lava lines, pink gauntlets and matching high-tops, plus temporary pink hair colour or a short pink wig. I'd keep both versions practical rather than playing it for laughs. Grey with fins and pink with lava still reads as the duo, whoever wears which.
9. Plus-Size Sharkboy And Lavagirl Costume
Stretch fabric does most of the work in a plus-size build. Sharkboy's breathable black base and straight-leg pants sit under a silver vest that adjusts at the sides, shaped with flexible foam teeth, side gills and a light fin held on wide elastic straps. I use wide elastic because narrow straps dig in and roll over the shoulder. Add grey gloves, cushioned boots and tousled hair. Lavagirl can start with a pink jumpsuit, an activewear set or a tunic and leggings. Curve the magenta panels and orange lava lines along the garment's own seams so they follow the body instead of stretching across it, then finish with a pink wig, boots, soft gauntlets and glowing makeup.
10. Budget Sharkboy And Lavagirl Costume
A thrift-store version can look sharp without any replica parts. For Sharkboy, look for a grey sports vest, a black long-sleeve shirt, dark pants, gloves and secondhand boots. Spray the vest silver with fabric spray paint, add felt teeth and make the fin from cardboard covered in grey fabric. Gel his own hair instead of buying a wig. For Lavagirl, a thrifted pink tracksuit gets orange ribbon and magenta felt, with a cheap pink wig, repainted sneakers, homemade foam wrist guards and pink makeup you already own. I always buy one extra piece of the same felt for both costumes, so the two characters share a texture and look made by one pair of hands.
11. No-Sew Sharkboy And Lavagirl Costume
No needle needed here: fabric glue, removable tape and hook-and-loop dots handle every join. Sharkboy's base is a black shirt, black pants and a grey utility vest, with pre-cut felt teeth and gills glued on and a felt-covered cardboard fin fastened to the vest with strong hook-and-loop strips. Lavagirl wears a pink shirt and leggings with peel-and-stick magenta and orange fabric shapes, plus a pink wig, boots and foam cuffs. Peel-and-stick shapes let go fastest at knees and elbows, so test every piece by bending and sitting the night before. Anything that lifts gets a dot of glue or a hidden safety pin.
12. Light-Up Sharkboy And Lavagirl Costume
Battery lights give the pair a superhero glow, as long as you keep them subtle. On Sharkboy, run cool white LED wire around the foam chest armour and arm cuffs and hide the battery pack in a vest pocket, over a black compression set, silver boot covers, gloves and a back fin. On Lavagirl, run pink or orange LED wire along the lava lines of a bright pink jumpsuit, with glowing cuffs, pink boots and a wavy wig. I hold the wire down with small stitches or clear tape rather than pins, which can poke through and catch skin. Use lights that stay cool, and keep them dim enough that the costume itself still shows. They look their best at an evening party once the room lights go down.
13. EVA Foam Sharkboy And Lavagirl Cosplay Costume
EVA foam is the material for anyone wanting proper dimensional armour. Under Sharkboy's layered silver-grey chest piece goes a black stretch bodysuit. Carve shallow teeth, ribs and gill lines into the foam, then heat the cuts lightly so they open up before you seal and paint. Add a reinforced dorsal fin, shaped forearm guards, fitted gloves, silver shin pieces and sturdy boots. Lavagirl's pink bodysuit carries light magenta torso armour with raised orange lava channels, shaped gauntlets, pink boot covers and a big wig. Hold the pieces on with elastic straps and contact cement, which flexes with the foam where hot glue snaps. A dirty grey wash on Sharkboy and a glossy finish on Lavagirl make the water-versus-fire contrast.
14. Comfortable Sharkboy And Lavagirl Tracksuit Costume
Matching tracksuits are the comfiest option on this list, and the one I'd pick for a long day. Sharkboy's charcoal zip-up jacket and joggers carry a silver shark-mouth chest panel, with a small fabric fin on the back, grey sneakers, soft gloves and wrist cuffs. Lavagirl's hot-pink tracksuit gets orange ribbon sewn on in flowing lava lines, plus pink sneakers, a shoulder-length wig and cushioned arm cuffs. I keep decorations clear of zips and pockets, because ribbon stitched across a zipper tape jams it the first time you try to open the jacket. Fleece tracksuits are also warm, so this pair suits school events and chilly evenings.
15. Warm-Weather Sharkboy And Lavagirl Costume
On a warm night, foam armour is the first thing to go. Sharkboy wears a sleeveless charcoal athletic top and knee-length black shorts with a thin silver foam chest panel, a small back fin, soft wrist guards and grey athletic shoes, plus styling paste in the hair and a little silver shading on the face. Lavagirl wears a fitted bright pink tee with a pink skater skirt or shorts, orange lava curves, light cuffs, pink sneakers and a breathable pink wig. Wigs are the hottest part of any costume, so I'd look for one with an open, wefted cap. Moisture-wicking base pieces and blush with shimmer instead of heavy face paint keep you cooler through an outdoor parade.
16. Cold-Weather Sharkboy And Lavagirl Costume
The trick in cold weather is putting the warmth under the costume, so a coat doesn't hide everything. Sharkboy gets thermal leggings and a fitted sweatshirt under a padded metallic vest, with insulated grey gloves, fleece-lined black pants, silver boot covers, a grey neck warmer and a charcoal ear warmer that leaves his hair showing. Lavagirl layers a pink thermal set under a roomy pink jumpsuit with magenta fleece panels, orange lava appliqués, warm wrist cuffs and pink snow boots, and wears the wig over a thin knit cap. I make the armour from fleece or soft foam here, because stiff foam stops a coat from closing over it.
17. School-Friendly Sharkboy And Lavagirl Costume
For a classroom, I strip the costume back to what can survive a school day. Sharkboy wears a grey sweatshirt with a felt shark mouth, black joggers, grey sneakers and soft wrist cuffs, and his small fabric fin is stitched flat to the back so he can lean on a chair. Loose spikes and a dab of silver face paint at the temples finish him. Lavagirl wears a pink long-sleeve tunic over leggings with orange fabric-tape lava lines, pink sneakers and soft arm bands. Temporary pink hair spray is simpler than a wig at school; if she does wear one, pin it well away from her eyes. Leave props, rigid armour and loose pieces at home, since many schools ask for that anyway.
18. Office Party Sharkboy And Lavagirl Costume
At the office, the characters can live in the colours and a couple of details. Sharkboy wears a charcoal button-down, black tailored trousers and a silver-grey vest with a small shark-mouth motif, plus a removable mini fin, grey shoes and silver wrist cuffs. Lavagirl suits a hot-pink trouser suit over an orange blouse, with curved lava trim along the blazer edges, pink loafers or block heels, a smooth pink bob wig and soft coral makeup. I attach the fin and trim with safety pins from the inside, so the suits go back to normal on Monday. The fin and wig come off in seconds once you need to get back to work.
19. Glam Sharkboy And Lavagirl Costume
This glam version swaps foam for metallic fabric and sequins. Sharkboy wears a silver fitted jacket over a black top and sleek black trousers, with shaped shark-mouth armour, mirrored wrist cuffs, a sparkly dorsal fin, gloves, silver ankle boots and cool shimmer around the eyes. Lavagirl wears a hot-pink sequin jumpsuit with orange crystal-like lava patterns, a long curled pink wig, glossy gauntlets and pink platform boots. Sequins are scratchy on the inside, so I line any sequin piece that touches bare skin with a soft knit. Give both costumes the same reflective finish, and keep the shapes slim so the sparkle doesn't swamp the characters.
20. Sporty Sharkboy And Lavagirl Costume
If the party involves games or dancing, build the pair from sportswear. Sharkboy starts with a charcoal compression top and grey training pants, then adds a breathable silver mesh vest with felt teeth, flexible fin accents, padded wrist guards and grey high-tops, with windswept hair and a touch of blue-grey on the face. Lavagirl wears a pink athletic jacket and leggings with orange piping that suggests moving lava, a high pink ponytail wig, cushioned cuffs and pink running shoes. Mesh is a good choice for the vest because it breathes, though felt teeth need a stitch at each point to stay on it. Leave off capes and anything that dangles.
21. Modest Sharkboy And Lavagirl Costume
Full coverage is easy with these two, since their looks are mostly colour and armour. Sharkboy wears a charcoal turtleneck, loose grey trousers and a long metallic tunic-style vest with white felt teeth, subtle gills, a flexible back fin, grey gloves and flat silver boots; a fitted grey hood can replace visible hair. Lavagirl wears a long pink tunic over wide-leg trousers, with magenta panels and orange lava curves running top to bottom. Long wrist guards, flat pink boots and a pink head covering or secured wig finish her. Vertical lava lines are my preference on a long tunic, because they draw the eye down the whole length rather than cutting it into blocks.
22. Maternity Sharkboy And Lavagirl Costume
For a pregnant Lavagirl, I'd skip tight armour and heavy pieces altogether. A stretchy hot-pink maternity dress or tunic with orange lava swirls flowing around the bump does the job, with supportive pink leggings, cushioned sneakers, soft wrist cuffs, a light wig and glowing coral makeup. A small removable lava heart pinned at the centre is a sweet touch. The Sharkboy partner wears a charcoal sweatshirt, black joggers, a silver foam vest, a flexible fin, gloves and grey sneakers. I make his vest adjustable with elastic or side ties so it's quick to loosen. Flat shoes and breathable layers matter more than any detail here.
23. Family Sharkboy And Lavagirl Costume
Adding Max and the Ice Princess turns the duo into a family set from the same film. Sharkboy and Lavagirl stay as above: grey armour with a fin for him, a pink lava jumpsuit with a wig and gauntlets for her. Max is the easy one, in a striped tee, casual jacket, jeans and sneakers, carrying a handmade dream journal. The Ice Princess wears a pale blue dress over warm leggings with silver boots, frosted makeup, a white wig and a light crystal headpiece. When I plan a family set, I match how saturated the colours are across all four costumes, so the bright pink doesn't make the pale blue look washed out.
24. Group Sharkboy And Lavagirl Costume
A bigger group can bring in Max, the Ice Princess and the film's villains. Sharkboy keeps his grey armour, black layers, fin, gloves, boots and messy hair, and Lavagirl her pink lava suit, bright wig, cuffs and pink footwear. Max wears everyday striped layers with a handmade dream notebook, and the Ice Princess a pale blue gown, frosted crown, white wig, crystal cuffs and silver flats. Extra friends can play Mr. Electric in a bright yellow structured suit, or Minus in a dark purple coat with geometric accents. With a group this size, I suggest everyone uses similar materials, felt with felt or foam with foam, so the whole set looks like it came out of one dream. Leave out realistic weapons and scary makeup.
25. Solo Sharkboy Costume
On his own, Sharkboy lives or dies by the dorsal fin, so give it the most care. Start with a fitted black long-sleeve shirt and black compression pants, then add a metallic silver vest with a wide shark mouth, white teeth, sculpted ribs and side gills. Attach the fin to the vest, not the shirt. A fin on a stretchy shirt flops sideways because the fabric has nothing to brace against. Fin-shaped arm guards, fingerless gloves, silver shin covers and black or grey boots finish the body, with messy spiked hair and cool grey shading on the cheekbones. Sit down, stand up and walk across the room in it before the party. If the fin tips, it's too heavy or too tall.
26. Solo Lavagirl Costume
Solo Lavagirl is all colour, so go bold with the pink. Start with a long-sleeve hot-pink jumpsuit, or a fitted top and leggings, and layer magenta foam panels across the chest, hips, forearms and shins. Paint or attach orange curves that look like lava trickling down the body. If you're painting, I use a flexible fabric paint and keep the lines fairly thin, since a wide band of paint on stretch fabric cracks once you move. Add a big wavy pink wig, pink arm guards, gloves and sturdy pink boots. Coral shadow, rosy blush and iridescent highlighter give a warm glow without full face paint, and a light translucent orange orb makes a good power prop. Brush the wig away from your face so you can see.
27. Sharkboy Hoodie Costume
A hoodie version suits anyone who hates jumpsuits and foam. Choose a charcoal zip-up hoodie and sew a soft grey dorsal fin along the back seam, where the double layer of fabric holds it upright better than a single panel. Add a removable silver chest panel with a black shark mouth and white felt teeth. Pair it with black joggers, grey fingerless gloves, silver wrist cuffs and charcoal high-tops, and put small fabric fins on the sleeves and lower legs if you like. Wear the hood down to show tousled hair, or sew soft teeth around its edge for a shark-bite effect. It's warm, washable and the most wearable costume here.
28. Lavagirl Dress Costume
A pink dress gives Lavagirl a softer, party-friendly shape. Pick a long-sleeve skater or A-line dress you can move in, then add magenta foam pieces at the shoulders, waist and wrists, and orange lava streams in fabric paint or removable appliqués. Opaque pink tights and sturdy pink ankle boots keep the colour running head to toe. Add a wavy pink wig, rosy eye makeup, a little iridescent highlighter and soft fingerless gloves, with a small glowing orange orb for photos. I keep the skirt near the knee and put fitted shorts underneath, since foam pieces at the waist tend to lift a short skirt when you raise your arms.
29. Retro 2000s Sharkboy And Lavagirl Costume
Lean into the decade the film came out with sporty Y2K shapes and shiny finishes. Sharkboy wears a black mock-neck, loose metallic cargo pants, a silver utility vest, wraparound glasses, wrist guards and chunky grey sneakers, plus a light fin and gelled, textured hair. Lavagirl pairs a hot-pink zip-up top with flared pink pants carrying orange lava appliqués, a layered pink wig, glossy cuffs, a small shoulder bag, platform sneakers and frosted pink makeup. Reflective vinyl brings the retro-future mood, but it doesn't stretch or breathe, so I'd use it for trims and panels rather than whole garments. The fins, lava lines and pink hair still tell everyone who you are.
30. Minimalist Sharkboy And Lavagirl Costume
The minimalist pair is about one strong detail each. Sharkboy wears a plain charcoal shirt and pants with a simple silver vest, a clean white shark-mouth graphic, a small dorsal fin, grey wrist cuffs, black gloves, silver sneakers and lightly tousled hair. Lavagirl wears a solid hot-pink jumpsuit with three or four bold orange lava curves, a sleek pink bob wig, slim gauntlets, pink ankle boots and soft coral makeup. Fewer, bigger shapes read better from across a room than lots of small ones. If you only have an evening to sew, make this pair, and they pack flat for travel too.
Lava Lines That Survive Stretch Fabric
Lavagirl's orange lava is the detail that makes her, and it sits on the stretchiest pieces in her wardrobe: leggings, jumpsuits, tracksuits. Each way of adding it behaves differently once the costume moves.
- Felt shapes look bold and are easy to cut, but felt doesn't stretch. Keep pieces small on leggings and stitch them down along the centre only, so the fabric can still give at the edges.
- Fabric paint blends nicely into the pink. Use a soft, flexible formula, stretch the fabric slightly while painting, and let it cure fully before wearing, or it cracks across the knees.
- Ribbon or bias tape sewn on with a zigzag stitch follows curves well and moves with knit fabric. It's what I use on tracksuits.
- Removable tape is fine for a few hours but lifts with body heat and bending, so treat it as a last-minute fix.
Pink Hair, Wig or Spray
A pink wig is the quickest way to make Lavagirl, but cheap ones tangle at the back and shed onto dark clothing, which matters if Sharkboy is standing next to you in black. Brush it gently before wearing and pin it at the nape over a wig cap. Temporary pink hair spray avoids the heat and itch of a wig, though it rubs off onto collars, pillows and car seats, so put an old towel over the headrest on the way home.
Silver Fins, Pink Lava and a Pair That Matches
Every version above rests on two colour stories and a few honest construction choices. Metallic grey, shark teeth, fins and arm guards make Sharkboy. Pink clothes, orange lava lines, bright hair and a warm glow make Lavagirl. Start with comfortable stretch basics, then pick felt, cardboard, fabric paint or EVA foam based on your time, budget and how much you enjoy crafting. Test the fin, the wig and every glued piece the night before, wear shoes you can walk in, and keep props light. Make both costumes to the same standard and the pair will hold together from the first photo to the last candy bar.
Related posts:
