Madrid, October 16 2026 - Halloween is heading beneath the surface at Atlantis Aquarium Madrid.

This year, the aquarium is taking inspiration from the mysteries of the sea to create a Halloween experience where mythology, familiar Halloween characters, and the marine world come together. Witches and mermaids are joined by a rather more unexpected character: Poseidon himself.

At the heart of the season is The Curse of the Dark Sea, an interactive marine adventure that brings a new Halloween story into the aquarium while connecting fantasy with the environmental themes that are part of the Atlantis experience.

It is a very different setting for Halloween – one where the mysteries hiding beneath the waves provide all the inspiration needed.

Paula Calatrava, Head of Education | DEI, Accessibility, Employee & Broader Society at Atlantis Aquarium Madrid, tells us more about the story behind Halloween 2026 and why guests might find themselves face-to-face with the god of the sea.

What makes Halloween at Atlantis Aquarium Madrid different from anywhere else?

It is Halloween with a distinctly marine twist.

At Atlantis Aquarium Madrid, we bring together spooky fun for children and familiar Halloween characters with the marine world and environmental themes that are relevant today.

The result is a Halloween celebration that feels very different from a traditional Halloween setting. The sea becomes part of the story, allowing us to combine fantasy and entertainment with the themes that are at the heart of Atlantis Aquarium Madrid.

If you could recommend just one Halloween experience that guests absolutely shouldn’t miss this year, what would it be – and why?

I would recommend The Curse of the Dark Sea.

It is the experience at the heart of our Halloween celebrations this year and offers guests something very different from what they might normally expect to find at an aquarium – or at Halloween.

It brings the marine theme, characters, and Halloween atmosphere together in one experience, creating a story for guests to discover as they explore Atlantis.

What are you introducing or doing differently for Halloween 2026?

For 2026, we are creating a Halloween-themed marine experience inspired by both mythology and classic Halloween characters.

Guests will encounter characters including Poseidon, witches, and mermaids, bringing together two worlds that might not immediately seem connected: Halloween and the mythology and mystery of the sea.

We want it to be fun, interactive, and original, while making the most of the very distinctive environment we have at Atlantis Aquarium Madrid.

Halloween takes months of work behind the scenes. What might surprise our guests about what it takes to transform the park for the season?

Probably the work that goes into developing the experience and creating a theme that makes sense specifically for Atlantis Aquarium Madrid.

Halloween has a very recognizable visual world, but our challenge is to reinterpret it through the marine environment. That means creating an experience where the characters, story, and theming all feel connected to the aquarium rather than simply adding traditional Halloween elements.

The aim is for guests to feel that Halloween has become part of the world of Atlantis.

Complete the sentence: “You haven’t really experienced Halloween at Atlantis Aquarium Madrid until you have…”

…met Poseidon in person.