UNDER [SI:] recounts the birth of the underwater ecomuseum in Cannes, near the southern shore of le Sainte-Marguerite. Six monumental statues are immersed between the Lérins Islands under the gaze of their creator, the sculptor Jason deCaires Taylor. Molded from the faces of six inhabitants of Cannes, these stone giants were made from an ecological marine material. If today, these statues constitute the first underwater eco-museum in France and the Mediterranean created by the artist, tomorrow they will serve as a habitat and refuge for local marine biodiversity. UNDER [SI:] brings to the screen the issues related to the preservation of the aquatic biodiversity thanks to interviews with specialists in marine biology and local actors. Alongside Jason deCaires Taylor, we discover the fragility and beauty of the Cannes underwater landscape. From the first castings of the faces in 2018 to the immersion of the 6 colossal statues in 2021, UNDER [SI:] highlights for the first time the stages of creation of the project, an intimate and a behind-the-scenes look which has established itself as real logistical and ecological challenge.