How do submersible work

On January 23, 1960, she reached the ocean floor in the Challenger Deep, carrying Jacques Piccard (son of Auguste) and Lieutenant Don Walsh, USN. This was the first time a ship, manned or unmanned, had reached the deepest point in the sea. The onboard systems indicated a depth of 37,800 ft (11,521 m), but this was later revised to 35,813 ft (10,916 m). (However later and more accurate measurements made in 1995 have found the Challenger Deep to be shallower, at 35,798 ft (10,911 m)). The descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the 3 hour 15 minute ascent. They observed small soles and flounders and noted the floor consisted of diatomaceous ooze while on the bottom.