Which support ship surveyed the Puerto Rico Trench before Victor Vescovo's 2018 dive?

The support ship that surveyed the Puerto Rico Trench before Victor Vescovo’s 2018 dive was DSSV Pressure Drop.

Pressure Drop—short for Deep Submergence Support Vessel—served as the surface platform for the Five Deeps Expedition. Its Kongsberg EM124 multibeam echosounder mapped the seafloor and helped identify the deepest target area before the crewed descent.

The ship’s work was more than simple navigation. Multibeam sonar sends sound pulses toward the seabed and measures their return time, producing a detailed bathymetric map. The expedition used those data to select the descent site, while the DSV Limiting Factor later verified the depth directly with pressure measurements.

A common mix-up is to name Limiting Factor as the survey vessel. Limiting Factor was the two-person submersible that carried Vescovo to the bottom; Pressure Drop was the larger support and mapping ship. The system also included robotic landers and scientific equipment for deep-ocean operations.