Stuff from googling:
But even with all the technology that we have today -- satellites, buoys, underwater vehicles and ship tracks -- we have better maps of the surface of Mars and the moon than we do the bottom of the ocean. We know very, very little about most of the ocean. This is especially true for the middle and deeper parts far away from the coasts.
Consider that we've sent 12 people to the moon since 1969 over a handful of missions; only three people have descended to the deepest part of the ocean in the Marianas Trench (And note that one of them was filmmaker James Cameron, who reportedly spent $10 million of his own money to finance the undersea craft). Even more shocking? The ocean takes up about 71 percent of Earth's space, yet a whopping 95 percent of that ocean is completely unexplored
