From mermaids and mermen to tropical fish, shark costumes and lobsters, we have plenty of ideas to choose from, suiting both kids and adults. The Under the Sea fancy dress theme allows you to explore your creative side, dressing the party with colourful seaweed and choosing a costume to match. Disney's popular movie The Little Mermaid is a common Under the Sea costume choice for kids and we have everything you need to get the celebration ready. Women may like to dress in a Mesmerising Mermaid costume, whilst little girls will love our authentic Ariel The Little Mermaid Costume. If you want to add a funny twist to the theme, how about dressing as Captain Birdseye and a Giant Fishfinger? It's a great couple's dress-up idea! Guys will definitely want to become Aquaman, and now you can with our movie-style Tribal Aquaman Costume. Browse our full collection of Under the Sea outfits and choose the perfect outfit for you. And don't forget to check out our Under the Sea accessories. Finish your costume with a trident prop or choose from a variety of colourful mermaid wigs.