Happy Happy, Carnage Carnage
The Catacombs, Elevation: -12.6m

General comments:

Ok back down on Happy Happy, Carnage Carnage head on over to that opposite ladder and head back up to We Can See In The Dark... Can You?.

Of course you could always take that secret teleporter to A Plague of Demons. But at this stage in the game you don't really know where that level is now do you? Want to take a chance?

Note that if you explore this level again the first door that closed behind you can now be opened. Here's a map of the full level with all doors open