system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why in 2014 is the ocean still such a mystery. We overcame obstacles to space travel 50+ years ago but can't figure out water.

I understand water pressure. I just wondered if there were any explanations as to why more money and effort hasn't been put into this over the years, or has it?

Edit: Thank you for your answers, and yes I am well aware that space is infinite and we have barely cracked the surface.  But just imagine if the "space race" never occurred and all the time/money/resources put into getting a man into space was spent on exploration of Earth's oceans.
gpt
We actually can do some pretty cool things in water.  We get oil from miles below a surface that is miles below the waves, we explore at tremendous depths, and we lay cables that stretch the length of the oceans. 

It's true that there's still a lot left to do, and we certainly could do a lot more.  But the reason we seem to be behind compared to space has less to do with pressure than with light (or electromagnetic waves more generally).  

The reason we know so much about space is that we can see really far, and what we see contains a lot of information in the form of light spectrums, positions, speeds, etc...  Also, most of the things we look at are really big, and stand out clearly from the background.  

Water, on the other hand, blocks all of that.  It scatters light, scatters heat, and makes info gathering a much more personal and in your face endeavour.