2001 – RV Melville – The 2.516-ton research vessel Melville at the time operated by the Scripps Institution of Oceanography took the Cook Expedition, Leg 6 with chief scientist Patricia Fryer of the University of Hawaii from Guam on 10 February 2001 to the Challenger Deep for a survey titled "Subduction Factory Studies in the Southern Mariana," including HMR-1 sonar mapping, magnetics, gravity measurements, and dredging in the Mariana arc region.[26][27] They covered all three basins, then tracked 120 nmi (222.2 km)-long lines of bathymetry East-West, stepping northward from the Challenger Deep in 12 km (7.5 mi) sidesteps, covering more than 90 nmi (166.7 km) north into the backarc with overlapping swaths from their SeaBeam 2000 12-kHz multi-beam echosounder and MR1 towed system. They also gathered magnetic and gravity information, but no seismic data. Their primary survey instrument was the MR1 towed sonar,[28] a shallow-towed 11/12-kHz bathymetric sidescan sonar developed and operated by the Hawaii Mapping Research Group (HMRG), a research and operational group within University of Hawaii’s School of Ocean and Earth Science and Technology (SOEST) and the Hawaii Institute of Geophysics and Planetology (HIGP).