The underwater scenes in Disney's The Little Mermaid (2023) were filmed using a sophisticated "dry-for-wet" technique. This method involved shooting the actors on land in front of blue screens at Pinewood Studios in London, rather than filming them underwater. The actors wore harnesses connected to rigs such as wires, teeter-totters, tuning forks, and circular rigs that allowed them to simulate the movements of swimming and floating underwater. These rigs enabled the actors to move freely in multiple directions, including spinning 360 degrees and moving vertically, to mimic underwater motion

. Only the actors' heads and arms were kept from the live-action footage; the rest of their bodies, including tails and hair, were created digitally. The filmmakers used computer-generated imagery (CGI) to animate the lower bodies and hair, allowing for controlled, aesthetically pleasing underwater movement that would be difficult to achieve naturally. Hair movement was carefully designed to flow softly or dramatically depending on the scene, avoiding unnatural flattening or obstruction of the actors' faces

. The sets, including King Triton's palace, Ariel's grotto, and Ursula's lair, were physically constructed on stage and inspired by extensive research into nautical footage and underwater environments. Lighting was crafted to simulate underwater caustics realistically, enhancing the illusion of being beneath the sea

. In summary, The Little Mermaid combined live-action performances on blue screen with advanced rigs and extensive CGI to create a believable underwater world, blending practical effects, choreography, and digital artistry in a method similar to that used in films like Aquaman