[zell12]

The tunnels are the long way to travel to the kingdom islands. Inexpensive to go through them, but if your low leveled and unexperanced with the dungeon, than I suggest using the ferry.
I'd post a map to show you what way to go but I reformated and I didn't feel like burning a bunch of graal stuff onto a CD, like my maps and stuff.
There are two entrances to the underground dungeon.
The first entrance:
Unstick to Bomboria and travel west towards Tanarthia, cross the river, and you should come to the wood choppin' place, contune following the path until you get like, 1/4 of the way to Tanarthia, and head up. The entrance is around there, you can even see it on your map.
The second entrance:
Unstick to Bomboria and then head east following the path, when you go up the hill and around the turn then head north and a touch east. You should come upon the dungeon around there somewhere.

I think the underground dungeon is a waste of time, the only good thing is the 4 Trex in the big room, and the other 3-5 (not sure) in the other ones.