Once Upon a Sea is a poetic, interactive XR documentary telling the tragic tale of the legendary Dead Sea. Through a physical exploration of the sea’s forbidden, moonlike landscapes, to intimate encounters with local characters, the user gets a rare glimpse into one of the world’s most dangerous, soon to be extinct, wonders. Centuries of human intervention and political neglect have turned the Dead Sea into a precarious place. Its water levels have dropped dramatically, leaving behind sinkholes and collapsing beaches. The experience offers a deep insight into the complexity and very human impact of this ecological and geopolitical crisis. Once Upon a Sea is our call to action.