In the last section of the caves, right at the end of the passage where you turn left and meet Dagoth Gares, the tunnel dead-ends.
The end of the tunnel isn't a wall but an impassable pile of boulders.
I can't fit through but I can look through the gaps in the rocks and there is definitely some sort of chamber back there, the map also hints at a wider room beyond.

After I had finished with Gares and his pals, I spent quite some time trying to figure out how to get in there, but there doesn't seem to be any way around the obstruction.

Anybody know what the deal is?

I don't believe there is anything in there. The way the game is laid out is that everything is of a standard size, and that things will be larger sometimes then what is needed for a particular scene, so it's submerged beneath the floor (rocks, stair cases) etc.. and some areas will have oddly colored blocks or piles of rocks sealing them off.

However, if you really want to check it out. You can always use the console command TLC or TCL I forget which one it is, that turns off the clipping in the game and allows you to walk through walls. Simple use the tilde "~" to bring up the console and type in TCL/TLC and then go through the wall look around then come back, and type it again to turn the clipping back on.

My Wood Elf squeezed in through the hole near the top (lots of jumping and left/fwd/right key movement) and found..... nothing [img]smile.gif[/img]

I was curious too because I was in that cave pre-Main Quest and did not find a single Dagoth anything or a high priestess (part of my Wood Elf's "Destroy Everthing 6th House so I can get a Good Night's Sleep" campaign). So I had to get in to see if maybe the Dagoth was hiding inside and could be killed [img]smile.gif[/img]

So I am not the only one that kills anyone claiming to be from the Sixth house. Ever since they have walked up to me on the street, I taunt them into attacking me then remove their pitiful existence. Fortunately this seems to have had good effect as I am not running into as many sleepers any more.

If you killed Dagoth, that means you got Corprus...ewww! Get away from me!