How can we conclude that “Challenger Deep” is the deepest part of the ocean. Does that mean we have explored all parts of the ocean?

Question

How can we conclude that “Challenger Deep” is the deepest part of the ocean. Does that mean we have explored all parts of the ocean?

In: 15

Answer 1

I believe that comprehensive soundings have been taken all over the world’s oceans. So, knowing the depth isn’t that difficult and, as long as all the ocean floor has been covered, we know all there is to know about that much.

Edit: plus, if you know where the world’s tectonic plates meet, and thus the subduction zones at plate edges, you can extrapolate that the deepest points will likely be around there.