(urth) Inhumi in the Whorl

[Andrew Mason]

Gerry Quinn wrote:

>> No need to bore. There are passages connecting the surface of the
>> Whorl to the interior, as part of the cooling system.
>
> And to the landers as well.  And perhaps other stuff.
>
> But there wouldn't be just holes open to space - they'd have to break in
> somehow.

Can anyone remember where the passage comes in which the cooling
system is explained? (It's filling up with water, which is why the
Whorl is getting overheated.) I want to check just what it says, but I
can't find it.