O’Brien said her dive scanned about a mile of desolate bottom terrain, finding that the surface is not flat, as once was thought, but sloping, and by about 18 ft (5.5 m), subject to verification, of course.[39][40][41][42] On 14 June 2020 Victor Vescovo and John Rost descended to the "Eastern Pool" of the Challenger Deep in the Deep-Submergence Vehicle Limiting Factor spending four hours at depth and transiting the bottom for nearly 2 miles.[43] On 20 June 2020 Victor Vescovo and Kelly Walsh descended to the "Western Pool" of the Challenger Deep in the Deep-Submergence Vehicle Limiting Factor spending four hours at the bottom. They reached a maximum depth of 10,923 m (35,837 ft). Kelly Walsh is the son of the Trieste’s captain Don Walsh who descended there in 1960 with Jacques Piccard.[44][45] On 21 June 2020 Victor Vescovo and Woods Hole Oceanographic Institution researcher Ying-Tsong Lin descended to the "Central Pool" of the Challenger Deep in the Deep-Submergence Vehicle Limiting Factor.