Rob Marshall has revealed the Under the Sea sequence in The Little Mermaid remake was “the most complicated musical number” he’s ever made.

Marshall has directed many musical numbers in films such as Chicago, Into the Woods and Mary Poppins Returns, however, he believes his latest movie, Disney’s live-action remake of The Little Mermaid, contains his most difficult one yet.

“(Under the Sea) is the most complicated musical number I’ve ever done,” he told Empire magazine.

The sequence is led by Ariel’s crab friend Sebastian, voiced by Daveed Diggs, and takes place on the seabed, with them surrounded by photorealistic CGI aquatic creatures.

While the creatures were digital, Marshall and his team referenced footage choreographed by the Alvin Ailey American Dance Theater troupe to get their movements just right.

“I wanted to create the entire musical number (with) their bodies,” Marshall explained. “I thought about (how) Walt Disney had worked with the Ballet Russe de Monte Carlo when he created Fantasia – he needs to work with dancers to use the S-shapes.”

The 62-year-old admitted the difficulty of making a live-action musical largely set underwater was part of the project’s appeal.

“How do you begin creating an underwater musical? It’s never been done before. That fear ignited something in me,” he shared, before explaining the rules of the musical.

“We introduce the singing underwater,” he said. “It’s very delicate, how you introduce song. It’s in this surreal world. We open the film above water, and then we go into this other world, and you accept those things immediately. You have to create the rules of how it works.”

The Little Mermaid, starring Halle Bailey, Melissa McCarthy and Javier Bardem, opens in cinemas on 26 May.

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