Looming large in Ambika P3’s mammoth 14,000 sq ft subterranean space, Italian filmmaker Martina Amati’s multi-screen installation is a remarkable sight to behold at the London gallery. Entitled Under, it immediately engulfs, plunging visitors into the mysterious sport (or art, as Amati would argue) of freediving.

The artist’s latest project, supported by the Wellcome Trust, sees her return to a subject that won her a Bafta for I Do Air in 2010: water. Under traces Amati and fellow freedivers (including record breaker Liv Philip) moving through silken blue waters off the coast of Egypt, performing acrobatics across ‘tightropes’, and descending through the depths of the Red Sea – all on a single breath of air.

In the gallery’s cavernous main hall, a horizontally suspended screen with projections on either side seemingly floats in the middle of the space, and can be viewed from a platform above or directly below. It’s an all-consuming visual centrepiece, with the screen so large that the film fills the viewer’s peripheral vision, making for a truly immersive experience.

Multiple zen-like projections are peppered throughout the rest of the space, while Icelandic composer and vocalist Gunnlaug Thorvaldsdottir has scored a suitably haunting soundtrack to accompany the installation. A final screen takes a more academic turn, airing a documentary in which Amati explores the physical effects of freediving, filmed in collaboration with Dr Kevin Fong, co-director of the Centre for Altitude, Space and Extreme Environment Medicine.

It’s a curiously enigmatic sport, with a small, tight-knit community and perhaps an unfair reputation for danger. Freediving was most recently thrown into the international spotlight following the presumed death of world champion Natalia Molchanova, who disappeared during a dive last month.

Nevertheless, Under brings the holistic side of freediving to the surface and it’s easy to see why Amati is so drawn to it. There’s a hypnotic stillness that’s impossible not to lose yourself in.