On 17 December 1967, Harold Holt, the Prime Minister of Australia, disappeared while swimming in the sea near Portsea, Victoria. An enormous search operation was mounted in and around Cheviot Beach, but his body was never recovered.

Holt was presumed to have died, and his memorial service five days later was attended by many world leaders. It is generally agreed that his disappearance was a simple case of an accidental drowning, but a number of conspiracy theories still surfaced, most famously the suggestion that he had been collected by a Chinese submarine.

While staying at his beach house, Holt suggested that a group of friends accompanies him to Cheviot Beach for a swim — it was about 12:15 p.m., and he wanted to cool down and work up an appetite before lunch. Holt knew the area well and had swum there many times before. Holt did not hesitate in entering the water, despite a large swell and visible currents. His friend Alan Stewart was the only other swimmer, as the others considered it unsafe.

Stewart stayed close to shore, and even in the shallows felt a strong undertow. However, Holt swam into deeper water and was dragged out to sea. The others called out to him, but he did not raise his arms or cry for help. He soon slipped under the waves and out of sight.

The Victoria Police were contacted and initiated what became one of the largest search operations in Australian history. By the end of the day, there were more than 340 personnel involved.

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