deepsea search
mm43
"That makes for five separate paths to the bottom, of which the engines can be considered as straight-down items."
I cant find good information on how they are searching, what sort of sensory equipment.There are laserlight camera's these days, which can be operated till 6000m or more, mounted on a ROV. Certain laserlight wavelengths will give distinguishable reflections on metal surfaces, and meanwhile penetrate deep enough through low density organic sediment layers.