Grimrock

I am so stupid...how do you get out of the abyss? i kinda fell in >_>

So i have explored just about every inch of this annoying place and I am looking for the second iron key to open the gate near the sign to the hamlet of Stormbreach and im stuck I already got the key from the slimes and i think its somewhere in the north western part of the map but i do not see a wa...