The deepest place in the World Ocean is 35,840 feet (nearly seven miles). This is the Challenger Deep in the Mariana Trench, about 200 miles southwest of the Pacific island of Guam. It was here in January 1960 that the U.S. Navy's bathyscaph Trieste dove to 35,800 feet.
Thirty-four years later, the unmanned Kaiko, Japan's newest remotely operated vehicle, returned to the site. It missed equaling the Trieste's record by only 14 feet. Since then, the Kaiko has made two other expeditions to this area but has not exceeded the manned record.
No human has returned to the deepest place in the sea since the two-man Navy team was there 42 years ago. Mount Everest, the highest place on our planet, has been climbed by more than 1,000 adventurers, and about the same number of astronauts have been in space. The moon's surface has been visited six times, and there is talk of a future manned mission to Mars. Yet, the greatest ocean depths on Earth are not accessible to manned inner spacecraft.