On December 17, 1967, Australia’s Prime Minister Harold Holt made the decision to take a swim. He was passing by Cheviot Beach, a longtime favorite spot for Prime Minister Holt to go swimming and snorkeling, with his traveling pals. Despite the slight turbulence in the water that day, Holt’s superb swimming ability allowed him to confidently dive into the ocean. His friends on land watched as he swam away from the beach and was carried out to sea “like a leaf” by a current. They called to him, but he showed no signs of distress or response. But before long, he disappeared behind the waves. His pals sounded the alarm.

Using police, Royal Australian Navy divers, Royal Australian Air Force helicopters, Army personnel, and local volunteers, the Australian people launched one of the biggest search missions in their nation’s history. However, neither the prime minister nor any information on his whereabouts was ever discovered. Being the only nation in history to have lost its head of state permanently is Australia. He had served as prime minister for nearly two years when he vanished.

Regarding the disappearance, a number of conspiracy theories surfaced, although no proof of these hypotheses has ever been discovered.

Today, a memorial plaque affixed to a reef submerged 50 feet below the surface of the ocean denotes the approximate location of his disappearance. In Melbourne, the Harold Holt Swim Centre bears his name.