Planets that are capable of sustaining human life are scarce. Putting aside the divisions on our maps, we have a total of one ocean. Since we have exactly one planet to live on and one ocean to sustain life, I'm gonna go ahead and call that pretty scarce. There's a massive amount of water but if we ruin that one ocean, I believe we all die.
So now it's time for a judgement call: what is so valuable at that depth that you're comfortable having people poke holes in it hoping to determine the science is good and worth the risk?