January 23: Men descended into the deepest point on earth (1960)

Location of Challenger Deep

On January 23, 1960, Trieste, the Swiss-designed and Italian-built bathyscaphe of the US Navy, descended to the deepest point known to exist on earth the Challenger Deep, with a depth of 10,902 m (35,786 ft) to 10,916 m (35,814 ft), in Mariana Trench near the Island of Guam. Trieste was manned by Jacques Piccard, one of the designers of the bathyscaphe, and Don Walsh, US Navy Lieutenant, and the descent took almost five hours and they spent about 20 minutes on the ocean floor before the three and a quarter hours of ascent. The measured depth from this experiment was 10,916 m (35,814 ft). This figure was known to be the most accurate measurement until the Japanese unmanned robotic deep-sea probe Kaiko made descents between 1995 and 1998. Kaiko's measured depth of the Challenger Deep was 10,911 m (35,797 ft). In 2009, the United States sent a hybrid remotely operated vehicle Nereus to the Challenger Deep. Nereus spent 10 hours at the bottom of the Challenger Deep and sent live video and data back to the mothership. Nereus measured a depth of 10,902 m (35,768 ft) at the bottom of the Challenger Deep.