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It's part of a mid-ocean ridge. They crisscross the globe like the seams on a baseball...thousands and thousands (millions even) of undersea volcanoes constantly erupting heating the oceans and spewing CO2 and other stuff into the water.

Human CO2 emissions and other 'pollution' don't even register by comparison.

There is also an entire bio-ecology that lives down there in the heat, having a good old time

yup...but not AN ecology...many, many,many separate ecologies that have never interacted with each other or the surface.

There could be a cure for cancer down there or a plague that wipes us out ;)

not likely...it's been isolated from us for hundreds of millions of years..

What do you mean? The cancer part or the bio danger part?

yes

those ecologies are rilly rilly ALIEN.
some of those critters that live there
don't even use hemoglobin for blood.

their blood is not red...it's blue.