The lower levels are optional. There are a couple points of interest in the first level, but you can come back for them later. The 3 pyramids activate a teleporter pad that takes you to the exit, but you you can skip them.
The exit is west. A shadow potion (you should have at least 1 if you washed the dishes for the cook in the castle) or a statuette would help running for the exit.
Iona's dungeon level 1 map (spoilers)
