Two children, Jacques Mayol (Bruce Guerre-Berthelot) and Enzo Molinari (), have grown up on the Greece island of Amorgos in the 1960s. Enzo challenges Jacques to collect a coin on the sea floor but Jacques refuses. Later, Jacques' father — who harvests shellfish from the seabed using Surface-supplied diving — goes diving. His breathing apparatus and rope gets caught and punctured by rocks on the reef and weighed down by water, he drowns. Jacques and Enzo can do nothing but watch in horror as he is killed.