Challenger Deep

The Trieste was a Swiss-designed deep-diving research bathyscaphe ("deep boat") with a crew of two, which reached a record-breaking depth of about 10,900 metres (35,761 ft), in the deepest part of any ocean on Earth, the Challenger Deep in the Marianas Trench, in January 1960. (This is near the Marianas Islands, including Guam.)

manned by Jacques Piccard (who co-designed the submersible along with his father, Auguste Piccard) and USN Lieutenant Don Walsh. The descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the three-hour-and-fifteen-minute ascent.

Since then, no manned craft has ever returned to the Challenger Deep.