La Piscine (The Swimming Pool)[4] is a 1969 psychological thriller film directed by Jacques Deray, starring Alain Delon, Romy Schneider, Maurice Ronet, and Jane Birkin.

Harry, an old friend and record producer who was Marianne's lover before Jean-Paul, arrives for a visit, surprising the couple by bringing along his 18-year-old daughter Penelope, whose existence they had not previously known about.

That night, while the women are asleep, Harry drunkenly confronts Jean-Paul and accuses him of seducing Penelope to revenge his own shortcomings on his more successful friend.

[8] Schneider had dramatically broken-up with Delon couple years earlier and married German director and actor Harry Meyen in Berlin.

During and after filming, Delon continued his relentless pursuit, and though Schneider repeatedly refused, their undeniable emotional connection translated into palpable on-screen chemistry.

[9][10] His efforts to win her back persisted long after the film, spanning much of her life and adding an emotional depth to their real and cinematic legacy.

[13] The Los Angeles Times called it a "handsome, stunningly designed film" which was at its best in "the deft way in which it coolly depicts how beautiful, chic people, dedicated to a sophisticate, amoral view of love, can be utterly defenseless against an onslaught of passion – a favorite Gallic theme.

"[14]The Guardian wrote: "Erotic languour turns gradually into fear and then horror in this gripping and superbly controlled psychological thriller" where "something in the very lineaments of the pool itself creates their own awful destiny: it is a primordial swamp of desire, a space in which there is nothing to do but laze around, furtively looking at semi-naked bodies.

"[17]Glenn Kenny of The New York Times commented, "Pretty people behaving poorly in beautiful settings is something we don’t see as much of in cinema as we used to.

[21] Alain Delon said in an interview that because his ex-lover Romy Schneider and good friend Maurice Ronet both died prematurely and under tragic circumstances, revisiting the film is simply too painful for him.

[22] The 2016 film A Bigger Splash, directed by Luca Guadagnino and starring Ralph Fiennes, Tilda Swinton, Matthias Schoenaerts, and Dakota Johnson, is loosely based on La Piscine.