Sorrows Furnace: only missions?

Sorrows Furnace reminds me somehow on UW: Until you enter a mission the doors are closed. Problem is that I simply like to explore without being slowed down by an NPC I have to protect. Is there a way to do this?

You can explore. I just took a party down there without taking an NPC and we spent awhile looking around. There WAS a NPC inside that has a quest (8000 exp, task is to kill a couple summit bosses i think). My party got ruined though -.- (necro summit would cast well of suffering on the spawn points and it only grew worse as the bodies piled up lol). Of course, I've done two of the main "protect the NPC" quests... Maybe that affects entrance to the furnace? DOn't know.

There's also another quest from a guy called galen trask where you can be a slave to the summit dwarves. The mission more and enough lets you fully explore the area with ease. I took some really good pics with that. it's just awesome.