How are we sure Challenger Deep is the deepest point when we have barely fully explored our ocean?

Question

Basically the title, but I always wondered if the Mariana Trench was the actual deepest point on our planet

In: 56

Answer 1

Recently i watched a video explaining things like that. Basically, what you say was true a few decades ago. Nowadays oceans are explored almost fully, but people still repeating the “fact” from ninetens.