I always wondered what the temperature was at the very bottom of the ocean. I assumed that it would be warm since it is closer to the center of the earth which is hot. I also thought that you could get a stick and poke it straight into the ground at this point. For some odd reason, I even thought that it would be a very thin, maybe a millimeter, layer of crust that would be scorching hot to the touch. Therefore, I decided to look into it. The answers I found surprised me.
The temperature is near freezing (0 degrees Celsius) at this depth. Furthermore, there are actually creatures that can live in these waters. The temperature of the water that come out of the underground vents can go well beyond boiling temperature. This is something that I find fascinating.
These creatures are gigantic compared to the ones at shallower depths and they thrive in this environment with hydrogen sulfide (H2S) gas. It is unfortunate that this gas is poisonous to humans. I would not have minded breathing in this gas if it made me eight feet tall.
Fissures and creatures in the hottest and one of the deepest parts of the ocean can be found at http://www.extremescience.com/deepcreat5.htm