Bastiaan Johan Christiaan "Bas Jan" Ader (born 19 April 1942 – disappeared 1975) was a Dutch conceptual artist, performance artist, photographer and filmmaker. He had lived in Los Angeles, California for the last twelve years of his life. His work was in many instances presented as photographs and film of his performances. He made performative installations, including Please Don't Leave Me (1969).Ader was lost at sea in 1975, attempting to cross the Atlantic Ocean from the US to England in the smallest boat ever. His deserted vessel was found off the coast of Ireland on 18 April 1976, offering few clues as to his fate.