The problem is time. There aren't that many multibeam sonar vessels in the world. They acquire data over narrow swaths. Mapping all ocean basins with multibe

The problem is time. There aren't that many multibeam sonar vessels in the world. They acquire data over narrow swaths. Mapping all ocean basins with multibeam would take a long time. I've always heard estimates of a few hundred years, though those were based on total the number of academic multibeam vessels operating 24/7. Obviously, it scales with the number of vessels you have doing it, so a large-scale coordinated effort that built lots of new, single-purpose vessels could take significantly less. At any rate, the cost of one survey made with one ship is not a good way to estimate the total cost, unless you're willing to wait a _really_ long time.