Bathyscaphe Trieste
On 23 January 1960, she reached the ocean floor in the Challenger Deep (the deepest southern part of the Mariana Trench), carrying Jacques Piccard and Don Walsh. This was the first time a vessel, manned or unmanned, had reached the deepest known point of the Earth's oceans. The onboard systems indicated a depth of , although this was revised later to ; fairly recently, more accurate measurements have found Challenger Deep to be between and deep.
Henry Morshead
In 1913 Frederick Bailey, an intelligence officer with the Indian Army, invited Morshead to be the surveyor in an expedition to explore the Yarlung Tsangpo Grand Canyon (Tsangpo Gorge), now known to be the world's deepest gorge.
Bailey and Morshead explored from the south with Morshead surveying the entire route and calculating the results as they went so as not to delay progress. By ascending the Dibang River they crossed the Himalayan watershed into Tibet to reach the Dihang River and ascending the Gorge.