Harold Holt, the 17th Prime Minister of Australia, disappeared on December 17, 1967, while swimming at Cheviot Beach near Portsea, Victoria. Despite an extensive search operation, which was one of the largest in Australian history involving police, military divers, helicopters, and watercraft, his body was never recovered. It is generally accepted that Holt drowned accidentally due to the rough sea conditions, though other possibilities like a shark attack have been suggested. Conspiracy theories, including one about him being taken by a Chinese submarine, also emerged but have no solid evidence. The official conclusion from a joint police report was that Holt's disappearance was accidental and not suspicious. His disappearance has become a well-known part of Australian history and folklore, and there is a memorial swimming center named in his honor. Holt's death led to John McEwen serving as caretaker Prime Minister, followed by John Gorton after a leadership election.