The Drunken Lizard Pub

I can't get through the blocked passage. I have tried blowing up the closest barrels with fire dart but it doesn't remove any stones. I can't target the further away barrels that I can see to the NW as it says target obscured. What am I doing wrong?

If you are where I think you are, the only way I know of is to go around.
I think of it as a quick way out, not in.
There is alot in the caves, look at everything and take your time,

Tom