Just lucky I guess conidering the technique you used to ask a basic question.
CJOK, the reason it took so long to initially answer your is that in order to give a factually accurate answer, we at the SDMB had to collectively run down to our local video shops and get a copy of the relevant documentary The Core, featuring Aaron Eckhart as Dr. Josh Keyes and Hillary Swank as Maj. Rebecca Childs.
Anyone attempting to answer without having watched the movie first would be just guessing, which is not permitted in this forum. You may notice the tentative and provisional nature of Colibri’s reply. His local Blockbuster had it already rented out.
How cold is the water at those depths? I do `t mean directly above these vents, I
mean overall. Is there simply too much water for it to turn to steam? 
That’s fine for posers and wannabees but most of us longtimers have video and print reference libraries at our house which has proven to be cheaper in the long run. I just hit fast forward, cross-check everything with some journals and reply back as soon as I am comfortable with my refresher knowledge.
Well done guys. Good improvisation! So thats why you were slower than you were with my previous posts.
Is there some oblique meaning to this that I am missing?
Just please don’t ask any questions about meteorites or NEAs (Near-Earth Asteroids). Netflix is reporting a very long wait for Armageddon.
A Wiki of the structure of the earths core.
In simple terms, lighter materials float on heavier ones.
Water is lighter than the core, or mantles or the crust.
Well, how long do you think caves last? Millions of years? Caves don’t last millions of years. And what happens to the water when a cave fills up with sediment? The water has to go somewhere else. Of course, there are really deep aquifers all over the world, but those aquifers don’t go down to the center of the earth. On time scales of millions of years solid rock will bend like play dough.
On geologic time scales light things end up on top of heavy things. Water is light. Rock is heavy. Put rocks and water into a box and the rocks sink to the bottom and the water floats over the rocks.
CJOK. Bumping your own thead five times in the first thirty minutes just isn’t allowed.
From our FAQ - Guidelines and Etiquette on the SDMB. Perhaps you should read all the sticky notes in ATMB, if you haven’t.
samclem GQ moderator
Please excuse me for my error, in my eagerness to get cracking, I had not given
your guidelines an adequate viewing but I will do that now. 
It’s not just a matter of “cold”. Water turns to vapor at 100C - and 1 atm of pressure (which is more or less the pressure you have at the beach). At higher pressures, water needs a higher temperature to boil; 10m of water height add another atmosphere, so water at the bottom of a 10m deep pool is under 2atm of pressure… water 200m below the ocean’s surface, at 21atm.
There is some boiling, but nothing, not even the smallest pot, boils instantly - much less the ocean. Put a pot of water to boil: there is a time, before it “breaks into a boil”, when small bubbles form on the walls and bottom of the pot. Those bubbles aren’t air, they’re water vapor (water that has boiled).
Some of the water that touches the lava (or the bottom of the hot pot) does indeed turn into vapor, but as it bubbles up, colder liquid water moves down… the bubbles eventually cool down again by sharing heat with the surrounding cold water (and become liquid again). Unlike in your pot, in the lava rifts the amount of heat that’s been transferred from the lava to the ocean is simply never enough to make it all boil. So yes, there’s simply too much water for it all to turn into steam.
My research material (Journey to the Centre Of the Earth) indicates that there should be at least enough space for a large amount of ocean to drain away. I realize that your material has a flashier presentation, but the science in mine is just as valid…
Si
Being aware that it is, and being aware why it is so, are two different things, do you not agree? :smack:
Here’s a thought experiment:
Take a beaker and fill it half way with a heavy liquid, like mercury. Then fill it the rest of the way with water. Will the water leak down into the mercury? No, because the mercury is a lot heavier. And since the mercury is liquid, there are no gaps for the water to leak into.
Thanks for that, but I am still wondering if this reply;
Originally Posted by Colibri
As far as I can recall, you are. …to my question;-
Originally Posted by CJOK
Surely I am not the 1st person to ask this question. You are usually much
swifter than this!
…was because no-one else had thought of it , or because as he seems to think,
the answer is that obvious, no-one would ask it. As he is not here yet, what do
you think? :dubious:
So I said this:-
…was that because no-one else had thought of it , or because as he seems to think,
the answer is that obvious, no-one would ask it. As he is not here yet, what do
you think?
and this:-
Being aware that it is, and being aware why it is so, are two different things, do you not agree?
sorry about exceeding my “bump” allowance!